Physics 124 Lab Manual
Datasheet
Lab-----------------------------Student Name-----------------------------Partner-----------------------------------Part I
Table1
Laser position
Incident angle
900
800
700
600
500
400
0
Reflection angle
0
10
10
20
20
30
30
40
40
50
50
300
60
60
Questions:
1. What relation do you see between the incident and reflected rays?
Equal but opposite, i.e. light at 80 degrees is reflected to the 100 degree mark.
2. State the Law that makes the prediction of the reflected angle possible if the incident
angle is known
First law of reflection
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Physics 124 Lab Manual
Part IA
Questions:
3. Where do the lines meet?
1 1/2 in behind mirror, 2 1/4 in from obj to mirorr
4. Write rules you could use to predict the location of the image if you had no mirror or
pins; just the original sheet of paper you were given.
The distance from the object to the mirror can be determined by drawing a line between two objects that
block the visual path of the original and finding their intersection.
Part IB
Questions:
5. How many images do you see?
90 deg: 3 images
45 degrees: 7 images
6. Write rules for locating all the images.
# of images = 360/angle -1
7. Explain why all the images are there.
Law of reflection
8. Is there a way to get more images with the two mirrors?
Make angle smaller
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Physics 124 Lab Manual
9. Explain the path of the light ray from the pin to the mirror and to the eye in all of the
experiments you have done.
Source of light -> object -> mirror -> reflected to viewer's eye.
Part IIA: Refraction Glass Prism
Table2
Glass Prism
Θ1(0)
Θ2 (0)
Θ3(0)
16
20
Θ4(0)
16
20
30
22
40
29
50
35
60
41
30
22
29
40
50
35
60
41
sinθ1
0.34
0.5
0.64
0.77
0.87
Question:
10. How do the four angles compare to each other for each experiment?
Angle 1 and 4 = 1.25 * angle 2 and 3
63
sinθ2
0.28
0.37
0.48
0.57
0.66
Physics 124 Lab Manual
Part IIB: Refraction Plastic Prism
Table 3
Plastic Prism
Θ1(0)
Θ2 (0)
20
30
Θ3(0)
6
6
12
12
40
15
50
21
60
Θ4(0)
24
sinθ1
20
30
0.34
0.5
15
40
0.64
21
50
0.77
60
0.87
24
sinθ2
0.104
0.207
0.258
0.358
0.406
Questions:
11. Do you find the same relationship when you compare the angles for the plastic prism?
No, angle 1 and 4 = 2.5 * angle 2 and 3
12. Plot a graph of sin θ1 versus sin θ2 and determine the slope for both the glass and the
plastic prisms
13. What is the significance of the slope of the graphs?
It is the refractive index of the materials
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Physics 124 Lab Manual
14. How do the slopes for glass and the prism compare?
Glass has a larger slope than plastic
15. How does Ө2, Ө 3, and Ө4 of the glass prism compare to Ө 2, Ө 3, Ө4, of the plastic
prism?
There is generally a larger difference between the angles in plastic than in glass.
16. What can you infer about how light travels through different materials?
Light travels slower through glass than plastic
17. Using your observations, can you write an equation that describes the relationships of
these angles?
Glass: angle 1 = angle 4; angle 2 = angle 3; angle 1 or 4 = 1.5 * angle 2 or 3
Plastic: angle 1 = angle 4; angle 2 = angle 3; angle 1 or 4 = 2.5 * angle 2 or 3
18. From your analysis describe in detail what you can infer about the behavior of light as it
is reflected and refracted.
Light slows when it is refracted, or perhaps more precisely, refraction is the result of light slowing.
Reflection sends light in an equal but opposite angle from the angle of incidence. When light is reflected
it continues at the same speed.
Submit all work / drawings along with the datasheet to your TA
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