PASCO EM-8622 User Manual

Includes

Teacher's Notes

and

Typical

Experiment

Results

Instruction Manual and
Experiment Guide for
the PASCO scientific
Model EM-8622

BASIC ELECTRICITY

MODEL

EM-8622

012-04367E

4/94

C

B

A

CW

D

E

C

+

-

+

-

© 1990 PASCO scientific $10.00

10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA

Phone [phone] • FAX [phone] • TWX 910-383-2040

better

ways to

teach physics

012-04367E Basic Electricity

T able of Contents

Section...........................................................................................................Page

Copyright, Warranty, and Equipment Return................................................. ii

Introduction .....................................................................................................1

Equipment........................................................................................................1

Getting Started, The Experiments ...................................................................2

Comments on Meters.......................................................................................3

Notes on the Circuits Experiment Board.........................................................4

Experiments

Experiment 1: Circuits Experiment Board .......................................5

Experiment 2: Lights in Circuits ......................................................7

Experiment 3: Ohm's Law ................................................................9

Experiment 4: Resistances in Circuits ............................................11

Experiment 5: Voltages in Circuits ................................................15

Experiment 6: Currents in Circuits.................................................19

Experiment 7: Kirchhoff's Rules ....................................................21

Experiment 8: Capacitors in Circuits..............................................23

Experiment 9: Diodes .....................................................................25

Experiment 10: Transistors...............................................................27

Appendix: Tips and Troubleshooting ...........................................................29

Replacement Parts List ..................................................................................31

Teacher's Guide .............................................................................................33

Technical Support................................................................................ Back Cover

i

Basic Electricity 012-04367E

Copyright, Warranty and Equipment Return

Please—Feel free to duplicate this manual
subject to the copyright restrictions below.

Copyright Notice

The PASCO scientific Model EM-8622 Basic Electricity
manual is copyrighted and all rights reserved. However,
permission is granted to non-profit educational institu­tions for reproduction of any part of this manual provid­ing the reproductions are used only for their laboratories
and are not sold for profit. Reproduction under any other
circumstances, without the written consent of PASCO
scientific, is prohibited.

Limited Warranty

PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workman­ship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return ship­ment will not be covered by the warranty.) Shipping
costs for returning the equipment, after repair, will be
paid by PASCO scientific.

Equipment Return

Should this product have to be returned to PASCO
scientific, for whatever reason, notify PASCO scientific
by letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instruc­tions will be promptly issued.

➤ NOTE: NO EQUIPMENT WILL BE AC-
CEPTED FOR RETURN WITHOUT AN AU­THORIZATION.

When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the
following rules:

➀ The carton must be strong enough for the item

shipped.

➁ Make certain there is at least two inches of packing

material between any point on the apparatus and the
inside walls of the carton.

➂ Make certain that the packing material can not shift in

the box, or become compressed, thus letting the instru­ment come in contact with the edge of the box.

Address: PASCO scientific

10101 Foothills Blvd.

Credits

This manual authored by: Clarence Bakken
This manual edited by: Dave Griffith
Teacher’s guide written by: Eric Ayars

P.O. Box 619011

Roseville, CA 95678-9011
Phone: [phone]
FAX: [phone]

ii

012-04367E Basic Electricity

Introduction

The PASCO Circuits Experiment Board is designed to
implement a large variety of basic electrical circuits for
experimentation. The Circuits Experiment Board can be
used for experiments beginning with a simple complete

Equipment

The PASCO Model EM-8622 Circuits Experiment Kit
includes the following materials:

(2) Circuits Experiment Boards,

(1) Resistor–– 3.3 Ω, 2W, 5%
(1) Potentiometer–– 25 Ω, 2W
(1) Transistor Socket
(32) Springs
(1) Battery Holder
(3) Light Sockets
(3) #14 Light Bulbs – 2.5 V, 0.3 A*
(1) Storage Tube

circuit and continuing on to a study of Kirchhoff’s Laws
and characteristics of diodes and transistors. A labeled
pictorial diagram of the Experiment Board appears in
Figure 1.2 of Experiment 1.

Instruction Manual and
Experiment Guide for
the PASCO scientific
Model EM-8622

BASIC ELECTRICITY

Copyright © November 1990 $10.00

MODEL

EM-8622

10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone [phone] • FAX [phone] • TWX 910-383-2040

012-04367A

3/91

better
ways to

teach physics

(1) Component Bag

Resistors

(2) 10 Ω–– 1 watt
(3) 100 Ω–– 1/2 watt
(8) 330 Ω–– 1/2 watt
(3) 560 Ω–– 1/2 watt
(3) 1000 Ω–– 1/2 watt
(2) 100 K Ω–– 1/2 watt
(2) 220 K Ω–– 1/2 watt

(2) Diodes 1N-4007
(2) Transistors 2N-3904
Capacitors

(2) 100 µ F–– 16 volts
(2) 330 µ F–– 16 volts

Wire Leads–– 22 ga.

(1) Experiment Manual

C

B

A

CW

D

C

E

+

-

+

-

* NOTE: Due to manufacturer's tolerances,
wattage may vary by 15-30% from bulb to bulb.

1

Basic Electricity 012-04367E

Getting Started

➀ Open the zip-lock bag containing the resistors and

other components. Distribute the following resistors
and wires to each of the boards, storing them in the
plastic holder at the top of the board:

(3) 5" Wire Leads (12.7 cm)
(4) 10" Wire Leads (25.4 cm)
(1) 100 Ω Resistor (brown, black, brown, gold)
(3) 330 Ω Resistors (orange, orange, brown, gold)
(1) 560 Ω Resistor (green, blue, brown, gold)
(1) 1000 Ω Resistor (brown, black, red, gold)

The Experiments

The experiments written up in this manual are develop­mental, starting from an introduction to the Circuits
Experiment Board and complete circuits, through series
and parallel circuits, ultimately resulting in diode and
transistor characteristics. These experiments can be used
in combination with existing labs that the teacher em­ploys, or may be used as a complete lab unit.

Experiment 1 Circuits Experiment Board

Store the remainder of the components in the zip­lock bag until needed in future experiments.

➁ Students will need to use the same resistors, same bat-

teries, etc. from one experiment to another, particu­larly during experiments 4 to 6. Labeling of the
boards and your meters will enable students to more
easily have continuity in their work. A pad has been
included on the board for purposes of labeling indi­vidual boards. Use of a removable label or using a
permanent marker are two alternatives.

Additional Equipment needed:

Experiments 3-10 Digital Multimeter, VOM or

VTVM (See discussion on page 3)

Experiments 8-10 The Meter needs at least 10

input impedance

Experiment 8 A timing device is needed,

0.1 second resolution.

6

Ω

Experiment 2 Lights in Circuits
Experiment 3 Ohm’s Law
Experiment 4 Resistances in Circuits
Experiment 5 Voltages in Circuits
Experiment 6 Currents in Circuits
Experiment 7 Kirchhoff’s Rules
Experiment 8 Capacitors in Circuits
Experiment 9 Diode Characteristics
Experiment 10 Transistor Characteristics

Experiment 9 A.C. Power Supply and an

Oscilloscope (optional)

2

012-04367E Basic Electricity

Comments on Meters

VOM:

The Volt-Ohm-Meter or VOM is a multiple scale, multiple
function meter (such as the PASCO SB-9623 Analog
Multimeter), typically measuring voltage and resistance,
and often current, too. These usually have a meter move­ment, and may select different functions and scales by
means of a rotating switch on the front of the unit.

Advantages: VOM’s may exist in your laboratory and
thus be readily accessible. A single meter may be used to
make a variety of measurements rather than needing
several meters.

Disadvantages: VOM’s may be difficult for beginning
students to learn to read, having multiple scales corre­sponding to different settings. VOM’s are powered by
batteries for their resistance function, and thus must be
checked to insure the batteries are working well. Typi­cally, VOM’s may have input resistances of 30,000 Ω on
the lowest voltage range, the range that is most often used
in these experiments. For resistances in excess of
1,000 Ω, this low meter resistance affects circuit opera­tion during the taking of readings, and thus is not usable
for the capacitor, diode and transistor labs.

DMM:

The Digital Multimeter or DMM is a multiple scale,
multiple function meter (such as the PASCO SB-9624
Basic Digital Multimeter or the SE-9589 General Purpose
DMM), typically measuring voltage and resistance, and
often current, too. These have a digital readout, often
with an LCD (Liquid Crystal Display). Different func­tions and scales are selected with either a rotating switch
or with a series of push-button switches.

Advantages: DMM’s are easily read, and with their
typically high input impedances (>10
for circuits having high resistance. Students learn to read
DMM’s quickly and make fewer errors reading values.
Reasonable quality DMM’s can be purchased for $60 or
less. PASCO strongly recommends the use of DMM’s.

Disadvantages: DMM’s also require the use of a battery,
although the lifetime of an alkaline battery in a DMM is
quite long. The battery is used on all scales and func­tions. Most DMM’s give the maximum reading on the
selector (i.e., under voltage, “2” means 2-volt maximum,
actually 1.99 volt maximum). This may be confusing to
some students.

6

Ω) give good results

VTVM:

The Vacuum Tube Voltmeter or VTVM is a multiple
scale, multiple function meter, typically measuring
voltage and resistance. They do not usually measure
current. The meter is an analog one, with a variety of
scales, selected with a rotating switch on the front of the
meter.

Advantages: VTVM’s have high input resistances, on
the order of 10
across a known resistance, current can be measured with
a VTVM.

Disadvantages: VTVM’s have multiple scales. Students
need practice to avoid the mistake of reading the incorrect
one. An internal battery provides the current for measur­ing resistance, and needs to be replaced from time to time.
Grounding problems can occur when using more than one
VTVM to make multiple measurements in the same
circuit.

6

Ω or greater. By measuring the voltage

Panelmeters:

Individual meters, frequently obtained from scientific
supply houses, are available in the form of voltmeters,
ammeters, and galvanometers (such as PASCO’s
SE-9748 Voltmeter 5 V, 15 V , SE-9746 Ammeter 1 A,
5 A and SE-9749 Galvanometer ± 35 mV). In some
models, multiple scales are also available.

Advantages: Meters can be used which have the specific
range required in a specific experiment. This helps to
overcome student errors in reading.

Disadvantages: Using individual meters leads to errors
in choosing the correct one. With limited ranges, students
may find themselves needing to use another range and not
have a meter of that range available. Many of the
individual meters have low input impedances
(voltmeters) and large internal resistances (ammeters).
Ohmmeters are almost nonexistent in individual form.

Light Bulbs

The #14 bulbs are nominally rated at 2.5 V and 0.3 A.
However, due to relatively large variations allowed by
the manufacturer, the wattage of the bulbs may vary by
15 to 30%. Therefore, supposedly “identical” bulbs may
not shine with equal brightness in simple circuits.

3

Basic Electricity 012-04367E

Notes on the Circuits Experiment Board

The springs are securely soldered to the board and serve
as a convenient method for connecting wires, resistors
and other components. Some of the springs are con­nected electrically to devices like the potentiometer and
the D-cells. In the large Experimental Area, the springs
are connected in pairs, oriented perpendicular to each
other. This facilitates the connection of various types of
circuits.

If a spring is too loose, press the coils together firmly to
tighten it up. The coils of the spring should not be too
tight, as this will lead to bending and/or breaking of the
component leads when they are inserted or removed. If a
spring gets pushed over, light pressure will get it straight­ened back up.

The components, primarily resistors, and small wires can
be stored in the plastic container at the top of the board.
Encourage students to keep careful track of the compo­nents and return them to the container each day following
the lab period.

When connecting a circuit to a D-cell, note the polarity
(+ or -) which is printed on the board. In some cases the
polarity is not important, but in some it will be impera­tive. Polarity is very important for most meters.

Connections are made on the Circuits Experiment Board
by pushing a stripped wire or a lead to a component into a
spring. For maximum effect, the stripped part of the wire
should extend so that it passes completely across the
spring, making contact with the spring at four points.
This produces the most secure electrical and mechanical
connection.

Spring

Wire

(top view)

(side view)

Figure 1 Diagram of wires and springs

4

012-04367E Basic Electricity

Experiment 1: Circuits Experiment Board

EQUIPMENT NEEDED:

-Circuits Experiment -Board

-D-cell Battery -Wire Leads

-Graph -Paper

Purpose

The purpose of this lab is to become familiar with the Circuits Experiment Board, to learn how to
construct a complete electrical circuit, and to learn how to represent electrical circuits with circuit
diagrams.

Background

➀ Many of the key elements of electrical circuits have been reduced to symbol form. Each symbol

represents an element of the device’s operation, and may have some historical significance. In this
lab and the ones which follow, we will use symbols frequently, and it is necessary you learn
several of those symbols.

Wire

Switch

Battery
(Cell)

Resistor

Light

Fuse

➁ The Circuits Experiment Board has been designed to conduct a wide variety of experiments easily

and quickly. A labeled pictorial diagram of the Experiment Board appears on page 6. Refer to
that page whenever you fail to understand a direction which mentions a device on the board itself.

➂ Notes on the Circuits Experiment Board:

a) The springs are soldered to the board to serve as convenient places for connecting wires,

resistors and other components. Some of the springs are connected electrically to devices like
the potentiometer and the D-cells.

b) If a spring is too loose, press the coils together firmly to enable it to hold a wire more tightly.

If a spring gets pushed over, light pressure will get it straightened back up. If you find a spring
which doesn’t work well for you, please notify your instructor.

c) The components, primarily resistors, are contained in a plastic case at the top of the board.

Keep careful track of the components and return them to the storage case following each lab
period. This way you will get components with consistent values from lab to lab.

d) When you connect a circuit to a D-cell (each “battery” is just a cell, with two or more cells

comprising a battery) note the polarity (+ or -) which is printed on the board. Although in
some cases the polarity may not be important, in others it may very important.

e) Due to normal differences between light bulbs, the brightness of “identical” bulbs may vary

substantially.

5

Basic Electricity 012-04367E

Procedure

➀ Use two pieces of wire to make connections between the springs on one of the light bulbs to

the springs on the D-cell in such a way that the light will glow. Discuss with your lab partner
before you begin actually wiring your circuit which connections you intend to make, and why
you think you will be successful in activating the light. If you are not successful, try in order:
changing the wiring, using another light, using another cell, asking the instructor for assis­tance.

a) Sketch the connections that the wires make when you are successful, using the symbols

from the first page of this lab.

b) Re-sketch the total circuit that you have constructed, making the wires run horizontally

and vertically on the page. This is more standard in terms of drawing electrical circuits.

➁ Reverse the two wires at the light. Does this have any effect on the operation? Reverse the

two wires at the cell. Does this have any effect on the operation?

➂ In the following steps, use a vacant spring

connection such as one of the three around the
transistor socket as shown on the right as a
“switch.” Connect one lead from the battery to
this spring and then take a third wire from the
spring to the light. You can now switch the
power “on” and “off” by connecting or not
connecting the third wire.

➤

Can be
removed

“Switch”

Figure 1.1

➤

➃ Use additional wires as needed to connect a second light into the circuit in such a way that it is

also lighted. (Use a “switch” to turn the power on and off once the complete wiring has been
achieved.) Discuss your plans with your lab partner before you begin. Once you have
achieved success, sketch the connections that you made in the form of a circuit diagram.
Annotate your circuit diagram by making appropriate notes to the side indicating what
happened with that particular circuit. If you experience lack of success, keep trying.

➤ NOTE: Is your original light the same brightness, or was it brighter or dimmer that it was

during step 1? Can you explain any differences in the brightness, or the fact that it is the
same? If not, don’t be too surprised, as this will be the subject of future study.

➄ If you can devise another

way of connecting two lights
into the same circuit, try it
out. Sketch the circuit
diagram when finished and
note the relative brightness.
Compare your brightness
with what you achieved with
a single light by itself.

➅ Disconnect the wires.

Return the components and
wires to the plastic case on
the Circuits Experiment
Board. Return the equip­ment to the location indi­cated by your instructor.

Storage
Box

Circuits Experiment Board

Model 555-04182-1 2 amp slow blow fuse

BOARD

Model EM-8622

CIRCUIT EXPERIMENT

KIT NO.

ABC

Light Bulbs Resistor (3.3 Ω)

Battery Holder

D cell

1.5 volts

D cell

1.5 volts

Potentiometer

Springs

Transistor
Socket

Figure 1.2

6

012-04367E Basic Electricity

Experiment 2: Lights in Circuits

EQUIPMENT NEEDED:

-Circuits Experiment Board -Two D-cell Batteries

-Wire Leads -Graph Paper.

Purpose

The purpose of this lab is to determine how light bulbs behave in different circuit arrangements.
Different ways of connecting two batteries will also be investigated.

Procedure

PART A

➤ NOTE: Due to variations from bulb to bulb, the brightness of one bulb may be substantially

different from the brightness of another bulb in “identical” situations.

➀ Use two pieces of wire to connect a single light bulb to one of the D-cells in such a way that the

light will glow. Include a “switch” to turn the light on and off, preventing it from being on
continuously. (You should have completed this step in Experiment 1. If that is the case, review
what you did then. If not, continue with this step.)

➁ Use additional wires as needed to connect a second light into the circuit in such a way that it is

also lighted. Discuss your plans with your lab partner before you begin. Once you have
achieved success, sketch the connections that you made in the form of a circuit diagram using
standard symbols. Annotate your circuit diagram by making appropriate notes to the side
indicating what happened with that particular circuit.

➤ NOTE: Is your original light the same brightness, or was it brighter or dimmer than it was

during step 1? Can you explain any differences in the brightness, or why it is the same?

➂ If one of the light bulbs is unscrewed, does the other bulb go out or does it stay on? Why or

why not?

➃ Design a circuit that will allow you to light all three lights, with each one being equally bright.

Draw the circuit diagram once you have been successful. If you could characterize the circuit
as being a series or parallel circuit, which would it be? What happens if you unscrew one of
the bulbs? Explain.

➄ Design another circuit which will also light all three bulbs, but with the bulbs all being equally

bright, even though they may be brighter or dimmer than in step 4. Try it. When you are
successful, draw the circuit diagram. What happens if you unscrew one of the bulbs?
Explain.

➅ Devise a circuit which will light two bulbs at the same intensity, but the third at a different

intensity. Try it. When successful, draw the circuit diagram. What happens if you unscrew
one of the bulbs? Explain.

➤ NOTE: Are there any generalizations that you can state about different connections to a set

of lights?

7

Basic Electricity 012-04367E

PART B

➆ Connect a single D-cell to a single light as in step 1, using a spring clip “switch” to allow

you to easily turn the current on and off. Note the brightness of the light.

⑧ Now connect the second D-cell into the circuit as shown in Figure 2.1a. What is the effect

on the brightness of the light?

➤
➤

➤
➤

Figure 2.1b

➤
➤

Figure 2.1cFigure 2.1a

⑨ Connect the second D-cell as in Figure 2.1b. What is the effect on the brightness?
➉ Finally, connect the second D-cell as in figure 2.1c. What is the effect on the brightness?

➤ NOTE: Determine the nature of the connections between the D-cells you made in steps

8-10. Which of these was most useful in making the light brighter? Which was least
useful? Can you determine a reason why each behaved as it did?

PART C

11 Connect the circuit shown in Figure 2.2. What

is the effect of rotating the knob on the device
that is identified as a “Potentiometer?”

Discussion

➀ Answer the questions which appear during the

experiment procedure. Pay particular attention
to the “NOTED:” questions.

Potentiometer

Light

Battery

➁ What are the apparent rules for the operation of

lights in series? In parallel?

➂ What are the apparent rules for the operation of

batteries in series? In parallel?

➃ What is one function of a potentiometer in a

circuit?

Figure 2.2 (Not to scale)

8

012-04367E Basic Electricity

Experiment 3: Ohm’s Law

EQUIPMENT NEEDED:

-Circuits Experiment Board -D-cell Battery

-Multimeter -Wire Leads

-Graph Paper.

Purpose

The purpose of this lab will be to investigate the three variables involved in a mathematical
relationship known as Ohm’s Law.

Procedure

➀ Choose one of the resistors that you have been given. Using the chart on the back, decode the

resistance value and record that value in the first column of Table 3.1.

Red (+)

Black (-)

Red (+)

Black (-)

Figure 3.1a

Figure 3.1b

➁ MEASURING CURRENT: Construct the circuit shown in Figure 3.1a by pressing the leads

of the resistor into two of the springs in the Experimental Section on the Circuits Experiment
Board.

➂ Set the Multimeter to the 200 mA range, noting any special connections needed for measuring

current. Connect the circuit and read the current that is flowing through the resistor. Record this
value in the second column of Table 3.1.

➃ Remove the resistor and choose another. Record its resistance value in Table 3.1 then measure

and record the current as in steps 2 and 3. Continue this process until you have completed all of
the resistors you have been given. As you have more than one resistor with the same value, keep
them in order as you will use them again in the next steps.

➄ MEASURING VOLTAGE: Disconnect the Multimeter and connect a wire from the positive

lead (spring) of the battery directly to the first resistor you used as shown in Figure 3.1b. Change
the Multimeter to the 2 VDC scale and connect the leads as shown also in Figure 3.1b. Measure
the voltage across the resistor and record it in Table 3.1.

➅ Remove the resistor and choose the next one you used. Record its voltage in Table 3.1 as in step

5. Continue this process until you have completed all of the resistors.

9

Basic Electricity 012-04367E

Data Processing

➀ Construct a graph of Current (vertical axis) vs Resistance.
➁ For each of your sets of data, calculate the ratio of Voltage/Resistance. Compare the values

you calculate with the measured values of the current.

Resistance, Ω Current, amp Voltage, volt Voltage/Resistance

Table 3.1

Discussion

➀ From your graph, what is the mathematical relationship between Current and Resistance?
➁ Ohm’s Law states that current is given by the ratio of voltage/resistance. Does your data

concur with this?

➂ What were possible sources of experimental error in this lab? Would you expect each to

make your results larger or to make them smaller?

Reference

Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White

0
1
2
3
4
5
6
7
8
9

1st Digit

2nd Digit

No. of Zeros

Tolerance

Fourth Band

None
Silver
Gold
Red

±20%
±10%
±5%
±2%

Figure 3.2

10

012-04367E Basic Electricity

Experiment 4: Resistances in Circuits

EQUIPMENT NEEDED:

-Circuits Experiment Boar

- Multimeter

-Resistors.

Purpose

The purpose of this lab is to begin experimenting with the variables that contribute to the opera­tion of an electrical circuit. This is the first of a three connected labs.

Procedure

➀ Choose the three resistors having the same value. Enter those sets of colors in Table 4.1 below.

We will refer to one as #1, another as #2 and the third as #3.

➁ Determine the coded value of your resistors. Enter the value in the column labeled “Coded

Resistance” in Table 4.1. Enter the Tolerance value as indicated by the color of the fourth band
under “Tolerance.”

➂ Use the Multimeter to measure the resistance of each of your three resistors. Enter these values

in Table 4.1.

➃ Determine the percentage experimental error of each resistance value and enter it in the appropri-

ate column.

Experimental Error = [(|Measured - Coded|) / Coded ] x 100%.

Colors

1st 2nd 3rd 4th Resistance

#1

#2

#3

Coded

Table 4.1

Measured

Resistance

%

Error

Tolerance

➄ Now connect the three resistors into the SERIES CIRCUIT, figure 4.1, using the spring clips on

the Circuits Experiment Board to hold the leads of the resistors together without bending them.
Measure the resistances of the combinations as indicated on the diagram by connecting the leads
of the Multimeter between the points at the ends of the arrows.

11

Basic Electricity 012-04367E

Series

R

1

R

2

R

3

R12=

➤

➤

R

12

➤

R

123

➤

R

23

➤
➤

R23=

R

123

=

Figure 4.1

➅ Construct a PARALLEL CIRCUIT, first using combinations of two of the resistors, and then

using all three. Measure and record your values for these circuits.

Parallel

➤ NOTE: Include also R

13

➆ Connect the COMBINATION

CIRCUIT below and measure
the various combinations of
resistance. Do these follow
the rules as you discovered
them before?

➤

R

1

R

12

R

2

➤

R12=

R23=

R

123

=

R

3

Combination

R

2

R

1

Figure 4.2

R1 =

R

3

R

=

23

R

=

123

➤

R

1

➤

➤

R

123

R

2 3

➤
➤

Figure 4.3

⑧ Choose three resistors having different values. Repeat steps 1 through 7 as above, recording

your data in the spaces on the next page. Note we have called these resistors A, B and C.

12

012-04367E Basic Electricity

Series

➤

➤

Colors

1st 2nd 3rd 4th

A

B

C

R

A

R

AB

➤

Coded

Resistance

Measured

Resistance

%

Error

Tolerance

Table 4.2

R

B

➤

R

ABC

R

C

R

=

AB

R

=

BC

R

BC

➤
➤

R

=

ABC

Parallel

➤

Figure 4.4

R

A

R

=

R

AB

R

B

R

C

➤

AB

R

=

BC

R

=

ABC

Figure 4.5

➤ NOTE: Include also R

AC

13

Basic Electricity 012-04367E

Combination

R

B

R

A

R

=

A

R

=

BC

R

=

ABC

➤

R

C

R

A

➤

➤

R

ABC

R

BC

Figure 4.6

➤

➤

Discussion

➀ How does the % error compare to the coded tolerance for your resistors?
➁ What is the apparent rule for combining equal resistances in series circuits? In parallel

circuits? Cite evidence from your data to support your conclusions.

➂ What is the apparent rule for combining unequal resistances in series circuits? In parallel

circuits? Cite evidence from your data to support your conclusions.

➃ What is the apparent rule for the total resistance when resistors are added up in series? In

parallel? Cite evidence from your data to support your conclusions.

Extension

Using the same resistance values as you used before plus any wires needed to help build the
circuit, design and test the resistance values for another combination of three resistors. As
instructed, build circuits with four and five resistors, testing the basic concepts you discov­ered in this lab.

Reference

Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White

0
1
2
3
4
5
6
7
8
9

1st Digit

2nd Digit

No. of Zeros

Tolerance

None
Silver
Gold
Red

Fourth Band

±20%
±10%
±5%
±2%

Figure 4.7

14

012-04367E Basic Electricity

Experiment 5: Voltages in Circuits

EQUIPMENT NEEDED:

-Circuits Experiment Board -Multimeter

-D-cell Battery -Resistors

-Wire Leads

Purpose

The purpose of this lab will be to continue experimenting with the variables that contribute to the
operation of an electrical circuit. You should have completed Experiment 4 before working on
this lab.

Procedure

➀ Connect the three equal resistors that you used in Experiment 4 into the series circuit shown

below, using the springs to hold the leads of the resistors together without bending them. Con­nect two wires to the D-cell, carefully noting which wire is connected to the negative and which
is connected to the positive.

➁ Now use the voltage function on the Multimeter to measure the voltages across the individual

resistors and then across the combinations of resistors. Be careful to observe the polarity of the
leads (red is +, black is -). Record your readings below.

Series

-

-

➤

-

+

V

1

R

1

➤

-

+

➤

V

12

➤

➤

Figure 5.1

R

=V

1

+

R

2

+

-

R

3

+

➤

V

23

V

123

=

1

➤

➤

R

=V

2

R

=V

3

R

=V

12

R

=V

23

R

=V

123

2

3

12

23

123

=

=

=

=

=

15

Basic Electricity 012-04367E

➂ Now connect the parallel circuit below, using all three resistors. Measure the voltage across

each of the resistors and the combination, taking care with the polarity as before.

➤NOTE: Keep all three resistors connected throughout the time you are making your
measurements. Write down your values as indicated below.

Parallel

+

-

R

➤

=

R

1

➤

V

1

R

2

R

3

1

R

=

2

R

=

3

R

=

123

V

=

1

V

=

2

V

=

3

V

=

123

Figure 5.2

➃ Now connect the circuit below and measure the voltages. You can use the resistance read-

ings you took in Experiment 4 for this step.

Combination

+

-

R

=

1

R

=

23

R

=

123

➤

➤

R

2

R

1

R

3

V

1

➤

➤

V

123

V

23

➤

➤

V

=

1

V

=

23

V

=

123

Figure 5.3

➄ Use the three unequal resistors that you used in Experiment 4 to construct the circuits shown

below. Make the same voltage measurements that you were asked to make before in steps 1
to 4. Use the same resistors for A, B and C that you used in Experiment 4.

16

012-04367E Basic Electricity

Series

R

ABC

+

R

B

-

++

C

➤

V

BC

-

➤

➤

-

-

+

V

A

R

A

-

+

V

AB

➤

V

Figure 5.4

R

=V

A

R

=V

B

R

=V

C

A

B

C

=

=

=

➤

➤

Parallel

➤

R

=V

AB

R

=V

BC

R

=V

ABC

+

-

R

=

R

A

➤

V

A

R

B

R

C

A

R

=

B

R

=

C

R

ABC

=

AB

=

BC

=

ABC

V

V

V

=

V

ABC

A

B

C

=

=

=

=

Figure 5.5

17

Basic Electricity 012-04367E

Combination

+

-

R

➤

➤

=

R

B

R

A

R

C

V

A

➤

V

ABC

➤

V

BC

➤

➤

A

R

=

BC

R

=

ABC

V

V

V

A

BC

ABC

=

=

=

Figure 5.6

Discussion

On the basis of the data you recorded on the table with Figure 5.1, what is the pattern for how
voltage gets distributed in a series circuit with equal resistances? According to the data you
recorded with Figure 5.4, what is the pattern for how voltage gets distributed in a series
circuit with unequal resistances? Is there any relationship between the size of the resistance
and the size of the resulting voltage?

Utilizing the data from Figure 5.2, what is the pattern for how voltage distributes itself in a
parallel circuit for equal resistances? Based on the data from Figure 5.5, what is the pattern
for how voltage distributes itself in a parallel circuit for unequal resistances? Is there any
relationship between the size of the resistance and the size of the resulting voltage?

Do the voltages in your combination circuits (see Figures 5.3 and 5.6) follow the same rules
as they did in your circuits which were purely series or parallel? If not, state the rules you see
in operation.

18

012-04367E Basic Electricity

Experiment 6: Currents in Circuits

EQUIPMENT NEEDED:

-Circuits Experiment Board -Digital Multimeter

-Resistors -D-cell Battery

-Wire Leads.

Purpose

The purpose of this lab will be to continue experimenting with the variables that contribute to the
operation of electrical circuits.

Procedure

➀ Connect the same three resistors that you used in Experiments 3 and 4 into the series circuit shown

below, using the springs to hold the leads of the resistors together without bending them. Connect
two wires to the D-cell, and carefully note which lead is negative and which is positive.

Series

➁ Now change the leads in your DMM so that

they can be used to measure current. You
should be using the scale which goes to a
maximum of 200 mA. Be careful to observe
the polarity of the leads (red is +, black is -). In
order to measure current, the circuit must be
interrupted, and the current allowed to flow
through the meter. Disconnect the lead wire
from the positive terminal of the battery and
connect it to the red (+) lead of the meter.
Connect the black (-) lead to R

, where the wire

1

originally was connected. Record your reading
in the table as Io. See Figure 6.2.

➂ Now move the DMM to the positions indicated

in Figure 6.3, each time interrupting the circuit,
and carefully measuring the current in each
one. Complete the table on the top of the back
page.

+

R

1

+

-

I

0

R

1

+

+

-

Figure 6.1

+

+

-

Figure 6.2

-

R

2

-

+

R

2

-

-

R

3

+

R

3

+

-

-

➤ NOTE: You will be carrying values from Experiments 3 and 4 into the table on the back.

19

Basic Electricity 012-04367E

-

R

1

+

I

0

+

I

1

+

-

-

R

2

+

-

-

I

3

+

I

2

R

3

Figure 6.3

I

R

=

1

R

=

2

R

=

3

R

=

12

R

=

23

R

=

123

=

0

I

=

1

I

=

2

I

=

3

V

=

1

V

=

2

V

=

3

V

=

12

V

=

23

V

=

123

➃ Connect the parallel circuit below, using all three resistors. Review the instructions for

connecting the DMM as an ammeter in step 2. Connect it first between the positive terminal
of the battery and the parallel circuit junction to measure I0. Then interrupt the various
branches of the parallel circuit and measure the individual branch currents. Record your
measurements in the table below.

Parallel

+

R

1

=

I

=

0

V

=

1

I

0

-

R

=

2

R

=

3

R

=

123

I

=

1

I

=

2

I

=

3

I

=

4

V2 =

V

3

V

123

=

=

Discussion

On the basis of your first set of data, what is the pattern for how
current behaves in a series circuit? At this point you should be able to summarize the
behavior of all three quantities - resistance, voltage and current - in series circuits.

+

-

R

1

R

2

R

3

Figure 6.4

-

I

4

+

+

+

-

I

1

-

I

2

-

I

3

+

On the basis of your second set of data, are there any patterns to the way that currents behave
in a parallel circuit? At this time you should be able to write the general characteristics of
currents, voltages and resistances in parallel circuits.

20

012-04367E Basic Electricity

Experiment 7: Kirchhoff’s Rules

EQUIPMENT NEEDED:

-Circuits Experiment Board -Two D-cell Batteries

-Wire Leads -Digital Multimeter (DMM)

-Resistors.

Purpose

The purpose of this lab will be to experimentally demonstrate Kirchhoff’s Rules for electrical
circuits.

Procedure

➀ Connect the circuit shown in Figure 7.1a using any of the resistors you have except the 10 Ω

one. Use Figure 7.1b as a reference along with 7.1a as you record your data. Record the
resistance values in the table below. With no current flowing (the battery disconnected), mea­sure the total resistance of the circuit between points A and B.

R

1

Wire

A

R

R

1

3

C

R

2

R

5

R

D

4

Figure 7.1a

B

Wire

AB

R

3

D

Figure 7.1b

➁ With the circuit connected to the battery and the current

C

flowing, measure the voltage across each of the resistors and record the values in the table below.
On the circuit diagram in Figure 7.1b, indicate which side of each of the resistors is positive
relative to the other end by placing a “+” at that end.

➂ Now measure the current through each of the resistors. Interrupt the circuit and place the DMM

in series to obtain your reading. Make sure you record each of the individual currents, as well as
the current flow into or out of the main part of the circuit, I

.

T

R

2

R

5

R

4

21

Basic Electricity 012-04367E

Resistance, Ω Voltage, volts Current, mA

R

1

R

2

R

3

R

4

R

5

R

T

V

1

V

2

V

3

V

4

V

5

V

T

I

1

I

2

I

3

I

4

I

5

I

T

Table 7.1

Analysis

➀ Determine the net current flow into or out of each of the four “nodes” in the circuit.
➁ Determine the net voltage drop around at least three (3) of the six or so closed loops. Re-

member, if the potential goes up, treat the voltage drop as positive (+), while if the potential
goes down, treat it as negative (-).

Discussion

Use your experimental results to analyze the circuit you built in terms of Kirchhoff’s Rules.
Be specific and state the evidence for your conclusions.

Extension

Build the circuit below and apply the same procedure you used previously. Analyze it in
terms of Kirchhoff’s Rules. If possible, try to analyze the circuit ahead of time and compare
your measured values with the theoretically computed values.

R

2

R

4

R

R

1

V

1

3

V

R

2

5

Figure 7.2

22

012-04367E Basic Electricity

Experiment 8: Capacitors in Circuits

EQUIPMENT NEEDED:

– Vacuum Tube Voltmeter (VTVM) or Elec­trometer (ES-9054B) or Digital Multimeter
(DMM) that has an input impedance of 10 MΩ
or greater.

Purpose

– Circuits Experiment Board
– Capacitors, Resistors
– Wire Leads

– D-cell Battery
– Stopwatch or timer with 0.1 sec resolution.

The purpose of this lab will be to determine how capacitors behave in R-C circuits. The manner in
which capacitors combine will also be studied.

Procedure

➀ Connect the circuit shown in Figure 8.1, using a 100-K Ω resistor and a 100-µF capacitor. Use one

of the spring clips from the transistor socket as a “switch” as shown. Connect the VTVM so the
black “ground” lead is on the side of the capacitor that connects to the negative terminal of the
battery and set it so that it reads to a maximum of 1.5 V DC.

➁ Start with no voltage on the capacitor and

the wire from the “switch” to the circuit
disconnected. If there is a remaining
voltage on the capacitor, use a piece of
wire to “short” the two leads together,
draining any remaining charge. (Touch
the ends of the wire to points B and C as
shown in Figure 1 to discharge the
capacitor.)

“Switch”

➤

A

Resistor

B

Capacitor

C

➂ Now close the “switch” by touching the

wire to the spring clip. Observe the
voltage readings on the VTVM, the
voltage across the capacitor. How would
you describe the manner in which the
voltage changes?

Figure 8.1

V

+

-

➃ If you now open the “switch” by removing the wire from the spring clip, the capacitor should

remain at its present voltage with a very slow drop over time. This indicates that the charge you
placed on the capacitor has no way to move back to neutralize the excess charges on the two
plates.

➄ Connect a wire between points A and C in the circuit, allowing the charge to drain back through

the resistor. Observe the voltage readings on the VTVM as the charge flows back. How would
you describe the manner in which the voltage falls? (It would be reasonable to sketch a graph
showing the manner in which the voltage rose over time as well as the manner in which it fell over time.)

➅ Repeat steps 3-5 until you have a good feeling for the process of charging and discharging of a

capacitor through a resistance.

➆ Now repeat steps 3-5, this time recording the time taken to move from 0.0 volts to 0.95 volts while

charging, t
your times along with the resistance and capacitance values in Table 8.1 at the top of the back page.

, and the time taken to move from 1.5 volts to 0.55 volts while discharging, tD. Record

C

23

Basic Electricity 012-04367E

Trial Resistance Capacitance

1

2

3

4

5

6

7

8

t

C

t

D

Table 8.1

⑧ Replace the 100-µF capacitor with a 330-µF capacitor. Repeat step 7, recording the charging and

discharging times in Table 8.1. If a third value is available, include it in the data table, too.

⑨ Return to the original 100-µF capacitor, but put a 220-K Ω resistor in the circuit. Repeat step 7,

recording your data in Table 8.1. If a third resistor is provided, use it in the circuit, recording the
data.

➤ NOTE:

➀ What is the effect on charging and discharging times if the capacitance is increased? What

mathematical relationship exists between your times and the capacitance?

➁ What is the effect on charging and discharging times if the resistance of the circuit is increased?

What mathematical relationship exists between your times and the resistance?

➉ Return to the original 100-K Ω resistor, but use the 100-µF capacitor in series with the 330-µF

capacitor. Repeat step 7, recording your results in Table 8.2.

11

Now repeat step 7, but with the 100-µF and the 330-µF capacitors in parallel.

R = __________ C

Type of Circuit

Series

Parallel

= __________C2 = __________

1

t

C

Table 8.2

t

D

➤ NOTE:What is the effect on the total capacitance if capacitors are combined in series? What if

they are combined in parallel? (Refer to Table 8.2).

24

012-04367E Basic Electricity

Experiment 9: Diodes

EQUIPMENT NEEDED:

-Circuits Experiment Board -Digital Multimeter (DMM)

-Wire Leads -Two D-cell Batteries

-1000-Ω Resistor -1N4007 Diode

-330-Ω Resistor.

Purpose

The purpose of this lab will be to experimentally determine some of the operating characteristics
of semiconductor diodes.

Procedure

➀ Connect the circuit shown in Figure 9.1a using the 1N4007 diode you’ve been supplied and the

1000-Ω resistor. Use Figure 9.1b as a reference along with Figure 9.1a as you record your data.
Note the direction that the diode is
oriented, with the dark band closer to
point B.

➁ With the “switch” closed and the current

flowing, adjust the potentiometer until
there is a voltage of 0.05 volt between
points B and C (V
voltage across the diode (VAB). Record
your values in the left-hand side of Table

9.1under “Forward Bias”.

). Measure the

BC

A

“Switch”

Diode

B

Resistor

C

➂ Adjust the potentiometer to attain the

following values for V

0.3,.....2.0 volts. Record the two volt-

ages for each case.

: 0.1, 0.2,

BC

Figure 9.1a

➃ Remove the 1000-Ω resistor and replace it with a 330-Ω

resistor. Repeat steps 3 & 4, going from a voltage of 0.3,

0.4,.....2.0 volts. Record the two voltages in each case.

➄ Reverse the orientation of the diode. Set the diode voltage

(V

) to the values 0.5, 1.0,....3.0 volts. Measure the

AB

resistor voltage (VBC) in each case. Record these values in
the columns labeled “Reverse Bias”.

Analysis

➀ Determine the current flow (I) in each setting by dividing

the voltage across the resistor (V
Where you switched resistors, be sure to change the divisor.

) by the resistance.

BC

➁ Construct a graph of Current (vertical axis) vs the Voltage across the diode, with the graph

extending into the 2nd quadrant to encompass the negative voltages on the diode.

AB

1N4007

C

R

Figure 9.1b

25

Basic Electricity 012-04367E

Discussion

Discuss the shape of your graph and what it means for the operation of a semiconductor
diode. Did the diode operate the same in steps 3 and 4 as it did in step 5? In steps 3 and 4
the diode was “Forward Biased”, while it was “Reverse Biased” in step 5. Based on your
data, what do you think these terms mean? What use might we have for diodes?

Sample Data Table

Diode Type ____________

Forward Bias Reverse Bias

R, Ω

VAB, volts VBC, volts

I, mA R, Ω

Table 9.1

VAB, volts

Extensions

➀ If your instructor has a zener diode, carry out the same investigations that you did above.

What differences are there in basic diodes and zener diodes?

➁ Use an LED (light emitting diode) to carry out the same investigations. What differences

are there between basic diodes and LED’s?

VBC, volts I, mA

26

012-04367E Basic Electricity

Experiment 10: Transistors

EQUIPMENT NEEDED:

-Circuits Experiment Board -Two D-cell Batteries

-Wire Leads -Digital Multimeter (DMM)

-1000-Ω Resistor -2N3904 Transistor (NPN)

-100-Ω Resistor.

Purpose

The purpose of this lab will be to experimentally determine some of the operating characteristics
of a transistor.

Procedure

➀ Connect the circuit shown in Figure 10.1a using the 2N3904 Transistor you’ve been supplied.

Resistor R

10.1a as you record your data. Note the leads on the transistor as marked next to the socket in the
drawing.

= 1000 Ω and resistor R2 = 100 Ω. Use Figure 10.1b as a reference along with Figure

1

b

Transistor as seen from
above

c

2N3904

A

R

1

B

b

e

c

2N3904

Figure 10.1a

C

D

R

2

e

Socket

R

1

AB

Figure 10.1b

➁ Adjust the potentiometer carefully until the reading between points A and B is approximately

0.002 volt (2.0 mv). Now read the voltage between points C and D. Record these readings in
your data table. Note that V
tor, while VCD divided by R2 gives the current flowing in the collector part of the circuit.

➂ Adjust the potentiometer to give V

corresponding V

0.060, 0.080, 0.100, 0.150, 0.200, 0.250 volts. Also set VAB to 0.000 volts.

: 0.006, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050, 0.055,

CD

divided by R1 gives the current flowing to the base of the transis-

AB

the following readings, each time reading and recording the

AB

R

2

CD

c

b

e

27

Basic Electricity 012-04367E

Analysis

➀ For each of your sets of readings, calculate:

I

= VAB / R1 and IC = VCD / R

B

Record all of your current readings in mA.

2

➁ Plot a graph of I

(vertical axis) vs IB. If you find an area or areas where you need more

C

points to fill out any curves or sudden changes, simply return to step 2 and make the appro­priate measurements.

➂ What is the general shape of the graph? Is there a straight-line region? Does it go through

the origin? Why or why not? Relate the behavior of the transistor at the beginning of the
graph to the behavior of the diode in Experiment 9.

➃ What does the leveling off of the graph indicate? Electronics people refer to the transistor as

being “saturated”. How would you describe saturation based on your experiment?

➄ Find the slope of the straight-line region of the graph. This ratio - I

/ IB is referred to as

C

the current amplification of the transistor. It describes how many times greater changes in
the collector current are than the changes in the base current. Report the current amplifica­tion of your transistor.

Discussion

Discuss the graph and the calculations you did in the Analysis section.

Sample Data Table

Transistor Type ____________

R1, Ω

VAB, volts IB, mA R2, Ω VCD, volts IC, mA

Table 10.1

Extensions

➀ What effect would changing the resistance in the collector circuit (R

the value to 330 Ω or 560 Ω. Does the graph have the same shape? Is the current amplifica­tion the same as before? How does the amplification depend on R

) make? Try changing

2

?

2

➁ Obtain a different transistor and repeat the measurements you made in steps 2 & 3. If it is a

PNP transistor, you will need to reverse the wires coming from the D-cells as the emitter
needs to be positive, not negative, and the collector will be negative.

28

012-04367E Basic Electricity

Appendix: Tips and T roubleshooting

Correct Circuit, Doesn’t Work

• Check to see if the circuit is indeed connected cor­rectly and completely.

• Check to see if the battery is giving full voltage.

• Check to see if each wire is making contact with the
spring. If magnet wire is used, the enamel coating
on the outside will prevent electrical connection and
needs to be removed. In some cases, students may
try to make a complete circuit through the insulation.

Surprising Results

In some cases, there will be no difference in the measure­ments from one point in the circuit to another. This
doesn’t mean the measurement is trivial or unimportant,
rather it is what we hope the student will learn from his/
her lab work. Not all measurements have to be different.

Making a “switch”

In the several labs, students are asked to use a “vacant”
spring connection such as one of the three around the
transistor socket as shown on the right as a “switch.” By
connecting one lead from the battery there and then
taking a third wire to the circuit, you can effectively
switch the power “on” and “off” by simply connecting or
not connecting the third wire. This duplicates the action
in a real switch.

➤

Can be
removed

“Switch”

➤

The labs asking for relative brightness ask students to
judge relative brightness only, not an absolute brightness.
This part of the experiment would be aided by having the
room mostly darkened. Additional bulbs can be pur­chased from PASCO, at Radio Shack, an electronics
store, at auto supplies stores, or possibly a local discount
store.

Batteries

The Circuits Experiment Board is designed to use one or
two D-cells. The voltage delivered by a D-cell is 1.5
volts ±. In practice, alkaline cells give the longest life,
but the less expensive zinc-carbon cells will give ad­equate results. A single set of batteries was used success­fully by ten different classes to complete labs 1,3,4,5, 6
and 7 before being replaced.

Resistors

The resistors supplied are listed under Materials on page
1 of this manual. The values have been chosen for clear
results and for helping to extend the life of the D-cells. If
resistors are lost or broken, replacements can be pur­chased from PASCO, or at any electronics store, includ­ing Radio Shack. Other values can be substituted, but for
Experiments 3 through 7, the values should be between
100 Ω and 1500 Ω for best results.

➤NOTE: Using the 330 Ω, 560 Ω and 1000 Ω

resistors gives approximate ratios of 1:2:3 for
working towards semi-quantitative understanding
of d.c. circuits.

The diagram below shows the resistor color code. For
example, a resistor having the colors Orange-Orange­Brown-Silver has the value 330 Ω ± 10%.

Figure 2

Lights and Relative Brightness

The lights for this experiment board, #14 bulbs, are
designed for 2.5 volts and 0.3 amperes. A single D-cell
will not light a bulb to maximum brightness, but two cells
in series will give a very bright light.

29

Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White

0
1
2
3
4
5
6
7
8
9

1st Digit

2nd Digit

Figure 3

No. of Zeros

Tolerance

Fourth Band

None

±20%

Silver

±10%

Gold

±5%

Red

±2%

Basic Electricity 012-04367E

➤

Wires

The Circuits Experiment Board can be used with a large
variety of wire types and sizes. We recommend 20 or 22
gauge solid wire with colorful insulation. This will help
students to follow their work more easily and minimize
difficulties in making the transition from paper circuit to
actual circuit on the Circuits Experiment Board.

Stripping Your Own Wire

The wire included with the Basic Electricity Lab is 22
gauge insulated, solid wire in 5" and 10" lengths. The
lengths are stripped at each end.

If you choose to strip your own additional wires, a
commercially available wire stripper can be used to
remove the insulation from each end. The jaws of the
wire stripper are placed on the wire 3/8" from the end.
By squeezing the handles together, the jaws will close on
the wire and cut only as deep as the insulation.

3/8"

➤

➤

Pulling the wire away from the stripper (Figure 3c) causes
the cut end of the insulation to slip off of the wire, leaving
3/8" of exposed wire.

Pull wire

Figure 3c

If you do not have access to a wire stripper, the wire may
also be stripped by carefully using a knife. Place the wire
on a solid surface. Set the knife blade on the insulation
about 3/8" from the end. With the blade at an angle so it
cannot cut downward into the wire, use the knife to shave
off the insulation.

Figure 3a

Squeeze
handles

➤

Figure 3b

➤

Figure 4

After one part of the insulation is removed, turn the wire
and continue shaving off the rest of the insulation.

➤

30

012-04367E Basic Electricity

Replacement Parts List

Item

P.C.B. ASSY, BASIC ELECT 004-04340
MANUAL EM-8622 012-04367
RES, 10 OHM, 1W, 5% 111-100
RES, 100 OHM, 1/2W, 5% 112-101
RES, 1K, 1/2W, 5% 112-102
RES, 100K, 1/2W, 5% 112-104
RES, 220K, 1/2W, 5% 112-224
RES, 330 OHM, 1/2W, 5% 112-331
RES, 560 OHM, 1/2W, 5% 112-561
CAP, ELECT-100mF, 16V AXIAL 222-039
CAP, ELECT 330MF, 16V AXIAL 222-040
DIODE-1N4007, 1000PIV, 1A 410-002
TRANSISTOR-2N3904 NPN 420-002

PASCO Part #

➤NOTE: Replacement parts can be purchased
from PASCO or at most electronic stores including
Radio Shack.

31

Basic Electricity 012-04367E

Notes

32

012-04367E Basic Electricity

Teacher's Guide

Exp 1 - Circuits Experiment Board

➀

➁ Reversing things at either end had no effect.
➃➄ There are two different ways of putting two

lamps into the circuit: parallel and serial.

Parallel:

Exp 2 - Lights in Circuits

➤NOTE: It is best to do these experiments with both
batteries, rather than just one. Connect them in series, as
shown in figure 2.1a. This will make the lights brighter
and easier to see when some of the dimmer circuits are
built.

Procedure

➀

With this method, the lights will each be approximately
the same brightness as in part 1.

Serial:

Using this circuit, the lights will be dimmer than in part 1.

➃➄

These circuits have the same characteristics as the ones in part
2-3

➅

Again, the circuit may be series or parallel.
Series Parallel

There are two ways of doing this as well.

➁➂

Series

The lights will be dimmer than in part 1. The electric current
must go through one bulb to reach the other, so disconnecting a
bulb will cause both to go out. (This is how those maddening
“if-one-goes-out-they-all-die-so-Merry-Christmas” lights are
wired.)

Parallel

The lights will show the same intensity as in part 1. The electric
current is going through both bulbs at the same time, so
disconnecting one does not affect the other. (This is how the
Christmas lights you wish you had bought are wired.)

There are two ways of making the circuit so that both

lights are on with the same intensity.

33

Parallel-in-Series Series-in-Parallel

a

(The parallel portion of the first circuit will be very dim.)
What happens if you unscrew one of the bulbs depends on

which bulb you unscrew. In the first circuit, unscrewing (a) will
turn everything off. Unscrewing (b) or (c) will make (a) dimmer
and leave the other one unaffected. In the second circuit,
unscrewing (c) will make (a) and (b) brighter; while unscrewing
(a) or (b) will make (c) brighter and turn the other one off.

➆-➉

11 The potentiometer, when used this way, adjusts the bright-

Putting the batteries in series (2.1a) will make things
the brightest, because then the voltage to the lights is the
highest. Batteries in parallel (2.1b) will have the same effect
as one battery. Batteries opposed (2.1c) will have no effect
at all unless one of the batteries is nearly dead.

ness of the lamp. (For best results, use the batteries in series
for this part of the lab.)

b

c

ab

c

Basic Electricity 012-04367E

Exp 3- Ohm's Law

Procedure

➁-➅)Warn the students to be particularly careful when

setting up the multimeter to measure current. Attach­ing an ammeter the wrong way can damage the meter.

Data Processing

Resistance Current Voltage V/R % difference

100 0.02 1.579 0.02 -1.87%
560 0.00 1.582 0.00 -2.73%
330 0.00 1.582 0.00 -3.32%

1000 0.00 1.583 0.00 -9.17%

10 0.14 1.549 0.15 -13.31%

Discussion

➀ Current is inversely proportional to R
➁ Yes. A curve fit of the graph above gives Current =

1.36 x Resistance
retical equation.

-0.98

, which is quite close to the theo-

0.16

0.14

J

0.12

0.1

0.08

Current

0.06

0.04

0.02

J

0

0 200 400 600 800 1000

J

Resistance

J

J

➂)The greatest source of error is caused by the meter it-

self. Because the ammeter has some internal resis­tance, the measured current is less than the current
when the meter is not there.

Exp 4- Resistances in Circuits

Procedure

➀-➃

Colors coded measured % error tolerance
#1 brown-black-brown-gold 100 98.9 -1.10% ±0.05%
#2 brown-black-brown-gold 100 99.6 -0.40% ±0.05%
#3 brown-black-brown-gold 100 99.7 -0.30% ±0.05%

➄ Series

R

= 198.3Ω

12

R

= 199.1Ω

23

R

= 298Ω

123

➅ Parallel

R

= 49.7Ω

12

= 49.9Ω

R

23

R

= 33.3Ω

123

R

= 49.8Ω

13

➆ Combination

R

= 98.9Ω

1

= 49.9Ω

R

23

= 148.7Ω

R

123

⑧ Series

R

= 428Ω

AB

RBC = 891Ω
R

ABC

Parallel

= 76.1Ω

R

AB

R

= 207Ω

BC

R

ABC

R

= 84.1Ω

AC

Combination

RA = 98.9Ω

= 207Ω

R

BC

R

34

ABC

= 989Ω

= 67.0Ω

= 306Ω

012-04367E Basic Electricity

Colors coded measured % error tolerance
A brown-black-brown-gold 100 98.9 -1.10% ±0.05%
B orange-orange-brown-gold 330 330 0.00% ±0.05%
C green-blue-brown-gold 560 561 0.18% ±0.05%

Discussion

➀ The actual value matches the coded value much more

closely than required by the tolerances.

Exp 5- Voltages in Circuits

Procedure

Equal Resistors:

Series

measurement Resistance Voltage

1 100 0.523
2 100 0.528

3 100 0.527
12 200 1.051
23 200 1.055

123 300 1.578

Parallel

measurement Resistance Voltage

1 33.33 1.565
2 33.33 1.565
3 33.33 1.565

123 33.33 1.565

Combination

measurement Resistance Voltage

1 100 1.049

23 50 0.529

123 150 1.578

Different Resistors:

Series

measurement Resistance Voltage

A 100 0.157

B 330 0.526
C 560 0.897

AB 430 0.685

BC 890 1.423

ABC 990 1.581

➁-➃ In series, the resistances are added.

R = R

+ R2 + R3 + ...In parallel, the reciprocals of the

1

resistances are added. 1/R = 1/R1 + 1/R2 + 1/R3 +...
This is evidenced in all the data sets above.

Parallel

measurement Resistance Voltage

A 67.49 1.574
B 67.49 1.574
C 67.49 1.574

ABC 67.49 1.574

Combination

measurement Resistance Voltage

A 100.00 0.509

BC 207.64 1.07

ABC 307.64 1.579

Discussion

1.6

1.4

1.2
1

0.8

Voltage

0.6

0.4

0.2

J

0

0 200 400 600 800 1000

J

In any series circuit, the voltage is distributed according
to the size of the resistors. (Notice that the graph above,
of the data from the second series circuit, shows this
direct relationship.)

In any parallel circuit, the voltage is the same across all
elements.

In the combination circuit, the voltage acts as if the
parallel resistors were actually one resistor, which is then
in series with the first. The rules are the same.

35

J

J

Resistance

J

J

Basic Electricity 012-04367E

Exp 6- Currents in Circuits

➤NOTE: The resistors used were:

R

= 100Ω

1

R

= 330Ω

2

R

= 560Ω

3

These are the same resistors as were used in the
previous lab, and some of the data here originates in
lab 5.

Procedure

Series:

The current was the same—1.5 mA—no matter where it
was measured in the circuit.

Parallel:

Measurement Resistance Current Voltage

1 100 0.0156 1.574
2 330 0.0047 1.574
3 560 0.0028 1.574

123 67.5 0.0229 1.574

Discussion

In any resistance circuit—series, parallel, or both—the
voltage, current, and resistance are related by Ohm’s
Law:

V = IR
This pattern, and conclusion, should be apparent in

student data.

➤NOTE: The product of the resistances and
currents obtained experimentally will generally be
lower than the measured voltage. This is due to the
non-zero resistance of the ammeter. When the
meter is in the circuit, its own resistance lessens the
current through that circuit. With most meters, this
error should be less than 5% or so.

Exp 7- Kirchoff's Rules

Procedure

First circuit:

12

+

+

34

R (Ω) V (V) I (mA)

1 100 0.40 3.9
2 560 1.17 2.0
3 330 1.05 3.1
4 100 0.52 5.1
5 330 0.65 1.9

T 216 1.57 7.1

+

+

5

+

Second circuit:

24

+

1

+

R (Ω) V (V) I (mA)

1 100 0.27 2.6
2 560 1.50 2.6
3 330 0.19 0.5
4 330 1.07 3.2
5 100 0.32 3.2
b1 1.573 2.6
b2 1.588 3.2

+

3

+

+

5b1

b2

36

012-04367E Basic Electricity

Analysis

First circuit:

➀ node (1,3): 0.1 mA

node (1,2,5): 0.0 mA
node (3,4,5): -0.1 mA
node (2,4): 0.0 mA

➁ loop (1,5,3): 0.001 V

loop (1,2,4,3): 0.001 V
loop (5,2,4): 0.000 V
loop (batt,1,2): 0.001 V
loop (batt,3,4): 0.000 V
loop (batt,1,5,4): 0.001 V
loop (batt,3,5,2): 0.000 V

Exp 8- Capacitors in Circuits

Second circuit:

➀ node (2,3,4): -0.1 mA

node (b1,3,5): 0.1 mA

➁ loop (b1,1,2,3) 0.001 V

loop (b2,5,3,4) 0.001 V
loop (b1,1,2,4,b2,5) 0.002 V

Discussion

Within the experimental uncertainty of the measuring
device used (a DMM) Kirchoff’s Rules are verified. The
net current flowing into or out of any junction is approxi­mately zero, and the sum of the voltages around any loop
is approximately zero.

Procedure

➃ The rate at which the capacitor loses its charge de-

pends on the impedance of the meter used to measure
the voltage, as well as on the size of the capacitor. For
this reason, most analog meters are not sufficient for
this lab.

➄

Charging

Voltage

Time

Voltage

Discharging

Time

➆ -11

140

1

120

100

80

60

Time (s)

40

20

0

0 50 100 150 200 250 300 350 400 450

➤NOTES:

➀➁ Charging: t = - R C ln(1-V/V

Discharging: t = - R C ln(V/V
In either case, the time is linearly dependent on

both resistance and capacitance.

➂ Parallel: C

Series: 1/Cs = 1/C1 + 1/C

100,000 Ohm

Z

220,000 Ohm

Z

Z

1

1

p

Capacitance (µF)

= C1 + C

)

o

)

o

2

2

Z

Z

1

1

37

Basic Electricity 012-04367E

Exp 9- Diodes

Analysis

0.007

0.006

0.005

0.004

0.003

Current

0.002

0.001

J

4007

O

LED

JJJJJJJJJJJJ

0

OOOOOO

J

J

J

J

J
J
J

J
J

J
J

J

J
J

J
J

J

J
J
J
J

J
J

J
J

J
J

J

J

J

J

J

OO OO

O

O

O
O
O

O
O
O
O
O
O

O

O

O

O

O

-3 -2 -1 0 1 2 3
Diode Voltage

Exp 10- Transistors

Analysis

➁

2N3904 Transistor

16
14
12
10

8
6

Collector Current (mA)

X

4

X

X

2

X

X

X

0

X

X

X

X

X

X

0 0.05 0.1 0.15 0.2

➂ The linear region does not include the origin, due to

the non-zero voltage that the junctions within the tran­sistor require to turn on. (Similar to the effect in lab 9)

➃ Beyond the “saturation point”, the transistor is acting

like a short circuit. It offers no resistance to the cur­rent; so beyond that point, there is no amplification.
The current is limited only by the battery and resistor.

➄ The current amplification of the transistor tested was

249. This value will vary from transistor to transistor;
it’s usually between 150 and 250 for the 2N3904 tran­sistors supplied with the lab.

100 Ohm load

X

X

X

X

X

X

Base Current (mA)

X

X

X

X

X

X

X

X

X

X

X

X

X

The diode acts as a one-way valve for electricity. Current
can flow in one direction, but not in the other.

Extensions

➀ A zener diode would be similar to the 4007, except

that there would be a breakdown point on the reverse
biasing, beyond which the current would flow. This
makes them useful for power regulation.

➁)The LED opens up at a higher voltage than the 4007

(and it lights up).

Discussion

➀ This graph shows the results of applying different val-

ues for R2. The amplification remains the same in
each linear region, but the size of that linear region
changes.

2N3904 Transistor

50

Ñ

10 Ohm load

Ç

40

47 Ohm load

Ö

100 Ohm load

á

560 Ohm load

30

Ñ

20

Collector Current (mA)

10

Ö

Ç

Ñ

Ö

Ç

Ñ

Ö

Ç

Ñ
Ö

á

Ç

á

á

á

Ñ

á

á

Ö

Ç

á

Ñ

Ö

Ç

Ö

Ñ

0

Ñ

Ç

Ç

Ñ

Ç

Ñ

Ç

Ç

Ñ

Ç

Ö

Ö

Ö

Ö

Ö

Ö

Ö

Ö

Ñ

Ç

Ö

Ö

Ö

Ñ

Ö

Ç

Ñ

Ö

Ö

Ç
Ñ

Ö

Ç

Ñ

á

á

á

á

á

á

á

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

various loads

Ñ

Ñ

Ñ

Ñ

Ñ

ÇÇ

Ñ

Ç

Ç

Ç

Ö

Ö

Ö

Ö

Ö

Ö

Ö

Ö

á

á

á

á

Base Current (mA)

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ñ

Ç

Ç

Ç

Ç

Ç

Ç

Ç

Ö

Ö

Ö

Ö

Ö

á

á

á

á

á

➁ The gain and/or saturation characteristics of the tran-

sistor will vary, although the basic shape of the graph
will remain the same.

38

Ñ

á

012-04367E Basic Electricity

T echnical Support

Feed-Back

If you have any comments about this product or this
manual please let us know. If you have any suggestions
on alternate experiments or find a problem in the manual
please tell us. PASCO appreciates any customer feed­back. Your input helps us evaluate and improve our
product.

To Reach PASCO

For Technical Support call us at 1-800-772-8700 (toll­free within the U.S.) or [phone].

email: [e-mail]
Tech support fax: [phone]
Web: http://www.pasco.com

Contacting Technical Support

Before you call the PASCO Technical Support staff it
would be helpful to prepare the following information:

• If your problem is computer/software related, note:
Title and Revision Date of software.
Type of Computer (Make, Model, Speed).
Type of external Cables/Peripherals.

• If your problem is with the PASCO apparatus, note:
Title and Model number (usually listed on the label).
Approximate age of apparatus.

A detailed description of the problem/sequence of
events. (In case you can't call PASCO right away, you
won't lose valuable data.)

If possible, have the apparatus within reach when call­ing. This makes descriptions of individual parts much
easier.

• If your problem relates to the instruction manual, note:

Part number and Revision (listed by month and year on
the front cover).

Have the manual at hand to discuss your questions.

39