Introduction to Reflection and Refraction

Statement of Purpose

To observe the behavior of light refracted and reflected and to measure the index of refraction of a semicircular plastic material.

Procedure

When the light ray hits the normal, the incident angle is 0, and the refraction angle is 0.

 Critical angle

Data

Step 1
 
θ1 θ2 sinθ1 sinθ2
0   0 0.000 0.000
5 3.5   0.087 0.061
10 5      0.174 0.087
15 9.3   0.259 0.162
20 12.6 0.342 0.218
25 16 0.423 0.276
30 17.5 0.500 0.301
35 22.2 0.574 0.378
40 25.5 0.643 0.431
45 28.5 0.707 0.477
50 31.5 0.766 0.522
55 35 0.819 0.574
60 37.5 0.866 0.609


Uncertainties (+/-)
uθ1 uθ2 usinθ1 usinθ2
1 1 0.017 0.017
1 1 0.017 0.017
1  1 0.017 0.017
1 1 0.017 0.017
1 1 0.016 0.017
1 1 0.016 0.017
1 1 0.015 0.017
1 1 0.014 0.016
1  1 0.013 0.016
1 1 0.012 0.015
1 1 0.011 0.015
1  1 0.010 0.014
1  1 0.009 0.014

mθ ≈ .64
sinθ1 vs sinθ2
msinθ ≈ .66

 sinθ1 vs sinθ2

θ1 vs θ2

Step 2


θ1 θ2 sinθ1 sinθ2
0 0 0.000 0.000
5 9.5 0.087 0.165
10 16.5 0.174 0.284
15 24.5 0.259 0.415
20 34 0.342 0.559
25 44 0.423 0.695
30 51.5 0.500 0.783
35 64.5 0.574 0.903
40 80    0.643 0.985


Uncertainties (+/-)
uθ1 uθ2 usinθ1 usinθ2
1 1 0.017 0.017
1 1 0.017 0.017
1         1 0.017 0.017
1 1 0.017 0.016
1 1 0.016 0.014
1 1 0.016 0.013
1         1 0.015 0.011
1 1 0.014 0.008
1         1 0.013 0.003

mθ ≈ 1.6
sinθ1 vs sinθ2
msinθ ≈ 1.5 

sinθ1 vs sinθ2

θ1 vs θ2

Conclusion
In the experiment we notice that we could not go beyond a particular angle of about 40 degrees, and this is known as the critical angle.