Introduction to Reflection and Refraction Lab

The purpose of this lab is to see how reflection and refraction work given a transparent medium and a ray of light. We were supplied with a semicircular plastic prism, a light box and a protractor to find the angle of incidence and refraction. We opted for using the protractor paper model at the end of the experiment guidelines.

We could observe that the angle of incidence of the ray was initially at zero. This meant that the angle of refraction was zero as well, causing the ray to travel back and forth in the same line.

We predicted that the light ray bends at the curved edge of the prism, because the wavelengths are sufficiently small with respect to the dimensions of the prism.

In this experiment light travels from a high density material (transparent prism) to a lower density material (air).

We proceeded to set up the equipment, and found out that the predictions were accurate.

We started to gather data and shift the angle in intervals of 7 and 6 degrees.

Trial	θ₁  (deg)	θ₂ (deg)	sin(θ₁)	sin(θ₂)
1	7	7	0.121869343	0.121869343
2	13	8.5	0.224951054	0.147809411
3	19	13	0.325568154	0.224951054
4	25.5	17	0.430511097	0.292371705
5	31	21	0.515038075	0.35836795
6	36	22.5	0.587785252	0.382683432
7	42	26.5	0.669130606	0.446197813
8	51	31.5	0.777145961	0.522498565
9	58	33	0.848048096	0.544639035
10	66	35.5	0.913545458	0.580702956

For the second graph, the slope came out to be 1.6258 which is the ratio of the index of refraction.

For the second case, we inverted the prism so that the rounded part would face the ray of light.

We assumed that if a light ray hit the curved surface first at the initial position showed above, the ray would not be distorted. It would travel back and forth along the path of the ray. 

When the ray strikes the flat surface, it will refract and it will bend the ray by an amount of degrees. 

The ray is still traveling from a high density to a lower density medium.

This time we made intervals of 6 and 7 degrees in between trials.

Trial	θ₁  (deg)	θ₂ (deg)	sin(θ₁)	sin(θ₂)
1	0	0	0	0
2	8	2	0.139173101	0.034899497
3	14	4	0.241921896	0.069756474
4	21	9	0.35836795	0.156434465
5	27	14	0.4539905	0.241921896
6	34	20.5	0.559192903	0.350207381
7	41	40	0.656059029	0.64278761
8	48	84.5	0.743144825	0.995396198
9	55	72.5	0.819152044	0.953716951
10	62	55.5	0.882947593	0.824126189
11	70	41	0.939692621	0.656059029

In Case 2 we found out that at approximately at 41 degrees, the light suddenly switched abruptly. This completely altered the graph making it look as if it had an asymptote, and getting rid of the continuity.

 When graphing sin(θ₁) vs sin(θ₂), a portion of the graph had a linear trend. The slope of the linear region came up to be 1.485 which was different to the slope obtained from case 1 (1.6258).