PASCO OS-8542 User Manual

Includes

Teacher's Notes

and

Typical

Experiment Results

Instruction Manual and

012-07105B

Experiment Guide for
the

PASCO scientific

Model OS-8542

BLACK BODY LIGHT SOURCE

FOR THE OS-8539 EDUCATIONAL

SPECTROPHOTOMETER

Black Body Instruction Manual 012–07105B

The exclamation point within an equilateral
triangle is intended to alert the user of the
presence of important operating and
maintenance (servicing) instructions in the
literature accompanying the device.

012–07105B Black Body Instruction Manual

Table of Contents

Section Page

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

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

Theory ...................................................................................................................................... 2-4

Setup ........................................................................................................................................ 5-8

Calibration ....................................................................................................................................9

Procedures .............................................................................................................................9-10

Experiment ........................................................................................................................... 10-11

Data Collection and Analysis ..................................................................................................... 12

Teacher’s Guide ................................................................................................................... 13-15

Troubleshooting ..........................................................................................................................16

Parts and Replacements .............................................................................................................17

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

i

Copyright, Warranty, and Equipment Return

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

Copyright Notice

The PASCO scientific 012-07105A manual is
copyrighted and all rights reserved. However,
permission is granted to non-profit educational
institutions for reproduction of any part of the 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 the 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. The 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 the product have to be returned to PASCO
scientific for any reason, notify PASCO scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and
shipping instructions will be promptly issued.

➤➤

➤

NOTE: NO EQUIPMENT WILL BE

➤➤

ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION FROM PASCO.

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 packing carton must be strong enough for the

item shipped.

➁ Make certain there are 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 cannot shift in

the box or become compressed, allowing the
instrument come in contact with the packing carton.

Address: PASCO scientific

10101 Foothills Blvd.
Roseville, CA 95747-7100

Phone: [phone]

FAX: [phone]

email: [e-mail]

web: www.pasco.com

ii

012–07105B Black Body Instruction Manual

Introduction

About this Manual

This manual describes setup, operational, and procedure guidelines for conducting a black body experiment
using the OS-8537 Educational Spectrophotometer, OS-8542 Black Body Light Source and the OS-8543 Black
Body Prism with Infrared Filter.

The Black Body Prism comes with the necessary accessories for mounting the prism onto the
spectrophotometer table of the PASCO OS-8537 Educational Spectrophotometer. The Black Body Prism is
designed to convert the PASCO Model OS-8539 Educational Spectrophotometer from a grating to a prism
spectrophotometer. A prism spectrophotometer has two advantages over a grating spectrophotometer: a) it
eliminates overlap of orders observed with a grating (When a grating is used, second order visible
wavelengths overlap first order infrared wavelengths.), and b) the spectrum is brighter because it does not
spread over several orders or in both directions.

Equipment Required:

• OS-8542 Black Body Light Source

• OS-8543 Black Body Prism with infrared filter, filter bracket and beveled stop piece

PASCO

BLACK BODY PRISM

OS-8543

Black body light source Prism mount with prism

Also Required:

• Educational Spectrophotometer System (OS-8539)

Filter bracket (with filter) for
the infrared light sensor

infrared
filter

• 0-10 VDC Power Supply (1 A) (SE-9720) Or Power Amplifier (CI-6552)

• Science Workshop Interface (Model 750 or 700)

Stop piece for the
light sensor arm

• PASCO Infrared Sensor (CI-6628)* Or High Sensitivity Light Sensor (CI-604)**

• DataStudio™ software

• Setup CD for the Black Body experiment

• 1 package containing 10 tungsten light bulbs (9 for replacement in the black body light source)

*Use the infrared sensor for black body experiments or when you want to measure infrared wavelengths.

**Use the high sensitivity light sensor for experiments in which only visible wavelengths are desired and a linear response is not needed.

1

Black Body Instruction Manual 012-07105B

Theory

The 60-degree prism is mounted so that the
back face is perpendicular to the incoming
light, as shown in Figure 1. A schematic of
the prism and the path of light is shown in
Figure 2 below. Since the prism angle is 60
degrees, it can be shown that

(1) θ2+ θ3=60°

And using Snell’s law at each interface,

(2) sin (60°) = n sin (θ2) and

(3) sin (θ) = n sin(θ3)

Combining equations (3) and (1) yields

(4) sin (θ) = n sin (60° – θ2)

which, using the double angle formula
becomes

black body light

light sensor

aperture slits

collimating slits

collimating lens

prism mount
with prism

GAIN

1

10

100

direction of light

Figure 1: Path of Light Through the Prism
Spectrophotometer

(5) sin (θ) = n{ sin (60°) cos (θ2) – sin (θ2) cos (60°)}

Now use a trig identity to change from cos to sin, and (5) becomes

1

(6) sin θ = n sin 60° 1 – sin2θ

2

– n sin θ2cos 60°

2

= sin 60° n2–n2sin2θ

If we now use (2), equation 6 becomes

1

(7) sin(θ) = sin(60°)[n2– sin2(60°)]

2

– sin(60°)cos(60°)

Solving (7) for n gives

(8) n =

sinθ

+ cos602+ sin260

sin60

And finally, if we simplify,

path of light

The Cauchy equation gives the relationship between the
wavelength and the index of refraction.

(10) n(λ)=

A

+ B

2

λ

where A and B depend on the type of glass.

1
2

– n sin θ2cos 60°

2

θ

3

θ

2

60°

n

60°

Figure 2: Schematic of a Prism

θ

2

012–07105B Black Body Instruction Manual

Table 1 shows the values for the prism used. The graph in Figure 3
shows an inverse square fit of the data.

Thus, we get the values of A=13,900 and B=1.689
with the wavelength given by

Thus, the final equation for the wavelength (in nanometers) is

Table 1: Prism Coefficients

ataD,stneiciffeoCmsirP

)mn(htgnelevaWxednInoitcarfeR

007.404677.1

008.534267.1

000.084847.1

001.684647.1

001.6454

006.785827.1

008.346227.1

003.656127.1

005.607717.1

001.258907.1

000.4101307.1

37.1

Figure 3: Relationship between refraction index
and wavelength for light passing through a prism

Determination of the Wavelength from the Angle (using DataStudio)

In DataStudio, the equation for determining the wavelength is listed in the Definition box in the Calculator
window, as follows:

Wavelength = filter (0,8000, (13900/(((1.1547*sin ((Init - Angle)/Ratio))^2 + 0.75)^0.5 - 1.689))^0.5)

where 0,8000 is the filtering range for the infrared light (0-8000 nm)

13,900 is constant A, as described above.

1.689 is constant B, as described above.

1.1547 is

2

3

Init - is the initial angle reading measured during data collection
Angle - is the angle measured by the rotary motion sensor
Ratio - is the ratio of the disk radius to the pin radius

3