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PS253 — Physics Lab for Engineers
In-Lab Worksheet, Introduction to Optics
Name: Robert Bryan
**Do not forget to hand this in before leaving class!
Refraction of Light and Snell’s Law
Using the internet, find a suitable reference for the index of refraction of air. Give relevant information here to reference your source and indicate any conditions that might apply to your value.
nair = __1.0002717___ Reference: RefractiveIndex.info Necessary Conditions: 15°C at 101.325 kPa.
Table 1: Measurements and calculated results for the index of refraction tests.
Θi
[°]
Θr
[°]
nr= nlens
Θi
[°]
Θr
[°]
nr= nlens
5
3.5
45
29
10
7
50
31.5
15
10.5
55
34.5
20
13.5
60
36.5
25
18
65
38.5
30
20
70
40.5
35
23.5
75
41.5
40
26
Standard Deviation of nlens:
Mean lens index of refraction:
Standard Deviation of Mean lens index:
Critical Angle Θi =44.5
Critical Angle test:
% Difference of nlens between methods:
Constructing a Collimated Light Source
Table 2: Focal length results of two trials using one lens
as a collimator and the second lens as a focuser.
Setup Method
f Lens 1
f Lens 2
Lens 1 is the collimator, Lens 2 is the focuser
18.1cm
10.1cm
Lens 2 is the collimator, Lens 1 is the focuser
19.5cm
10.4cm
Mean
18.8
10.25
Testing Convex Lenses and the Thin Lens Equation
Using the Mean f for Lens 1 from above, solve the thin lens equation for when do = di to find a starting separation distance:
Table 3: Measurements and calculated results
for thin lens focal length tests on Lens 1.
Trial
dobject
[cm]
dimage
[cm]
flens
[cm]
hobject
[cm]
himage
[cm]
flens
[cm]
Mexp
Mth
% Difference of M
do = di
40.35
40.35
4.2
4.0
do < di
28.0
72.0
4.2
10.75
do > di
55.0
32.0
4.2
2.5
Show your work to calculate the focal length, magnifications, and %difference of Lens 1 for the do = di trial.
Using the Mean f for Lens 2 from the Collimated Light Source section, solve the thin lens equation for when
do = di to find a starting separation distance:
Table 4: Measurements and calculated results
for thin lens focal length tests on Lens 2.
Trial
dobject
[cm]
dimage
[cm]
flens
[cm]
hobject
[cm]
himage
[cm]
flens
[cm]
Mexp
Mth
% Difference of M
do = di
20.0
20.0
4.2
12.2
do < di
14.0
35.0
4.2
10.5
do > di
61.0
12.0
4.2
0.9
Show your work to calculate the focal length, magnifications, and %difference of Lens 2 for the do = di trial.
Table 5: Summary of focal length results for two lenses using five various methods.
Setup Method
f Lens 1
f Lens 2
Lens 1 is the collimator, Lens 2 is the focuser
Lens 2 is the collimator, Lens 1 is the focuser
do = di
do < di
do > di
Mean
Standard Deviation of Mean
Note: ,
Constructing a Simple Refracting Telescope
Draw a diagram below similar to those in the lab module representing your constructed telescope. You should include figures for the two lenses, the distant object, your eye (think of it like third lens), and where the image is formed. Label the lenses eyepiece and objective and indicate the focal length of each, label the object distance and the image distance.
Theoretical Telescope Magnification =
Table 6: Results of constructing and observing through a simple refracting telescope.
Partner 1 Mexp
Partner 2 Mexp
Partner 3 Mexp
Partner 4 Mexp
2.0
2.0
2.0
2.0
Describe two possible sources of error that could have affected your results during the Snell’s Law and Critical Angle tests of the index of refraction experiments. You can describe more than two, but only one instance of measurement error will count. Try to think of other sources of error.
Describe two possible sources of error that could have affected any of your work with the thin lenses and subsequent results. You can describe more than two, but only one instance of measurement error will count. Try to think of interesting or unique sources of error specific to this experiment.
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