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 (916) 786-3800 • FAX (916) 786-8905 • 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: (916) 786-3800
FAX: (916) 786-8905
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 (916) 786-3800 • FAX (916) 786-8905 • 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
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