lab lab lab lab
Lab #5: Refraction of Light
Theory: Refraction can be defined as the bending of a wave when it enters a medium which causes it to have some reduced speed. In terms of light, refraction occurs when the ray passes through some medium which slows its speed; such as water or glass. In this instance the ray tends to bend towards the normal of the medium. The amount of bending or refraction which occurs can be calculated using Snell's Law ().
Objective: To measure the index of refraction of Lucite and to verify Snell’s Law.
Materials: Lucite block, light ray box, paper, pencil, ruler and protractor.
Procedure: First, place the refraction block on a piece of paper and draw an outline of the block. Second, draw a line perpendicular to the horizontal dimension of the block diagram at the center and extend this line 1 cm across the boundary. Third, use the light ray box to direct the incident light beam to the air-block boundary at an angle with respect to the normal. Observe the direction of the transmitted beam inside the block and the emerging beam at the block-air boundary. Next, use a ruler to draw a line to coincide with the path of the incident light beam. This is the direction of the incident ray. After that, use a ruler to draw a line to coincide with the path of the emerging light beam. This line represents the direction of the emerging light ray. Remove the block from the paper and use a ruler to draw a straight line from the terminal point of the incident ray to the point of origin of the emerging ray. This ray represents the direction of the transmitted beam inside the block. Next, use a protractor to measure the angles of incidence and refractions. Lastly, determine the index of refraction of the medium in which light is traveling, ni, and the index of refraction in the second medium, nr.
Θi
Θr n1 ≈ Θi / Θr
Sin Θi
Sin Θr n2 = Θi / Θr
5
2.5
2
0.087
0.044
1.977
10
7.5
1.33
0.174
0.130
1.338
15
11
1.36
0.258
0.191
1.351
Avg =
Theory: Refraction can be defined as the bending of a wave when it enters a medium which causes it to have some reduced speed. In terms of light, refraction occurs when the ray passes through some medium which slows its speed; such as water or glass. In this instance the ray tends to bend towards the normal of the medium. The amount of bending or refraction which occurs can be calculated using Snell's Law ().
Objective: To measure the index of refraction of Lucite and to verify Snell’s Law.
Materials: Lucite block, light ray box, paper, pencil, ruler and protractor.
Procedure: First, place the refraction block on a piece of paper and draw an outline of the block. Second, draw a line perpendicular to the horizontal dimension of the block diagram at the center and extend this line 1 cm across the boundary. Third, use the light ray box to direct the incident light beam to the air-block boundary at an angle with respect to the normal. Observe the direction of the transmitted beam inside the block and the emerging beam at the block-air boundary. Next, use a ruler to draw a line to coincide with the path of the incident light beam. This is the direction of the incident ray. After that, use a ruler to draw a line to coincide with the path of the emerging light beam. This line represents the direction of the emerging light ray. Remove the block from the paper and use a ruler to draw a straight line from the terminal point of the incident ray to the point of origin of the emerging ray. This ray represents the direction of the transmitted beam inside the block. Next, use a protractor to measure the angles of incidence and refractions. Lastly, determine the index of refraction of the medium in which light is traveling, ni, and the index of refraction in the second medium, nr.
Θi
Θr n1 ≈ Θi / Θr
Sin Θi
Sin Θr n2 = Θi / Θr
5
2.5
2
0.087
0.044
1.977
10
7.5
1.33
0.174
0.130
1.338
15
11
1.36
0.258
0.191
1.351
Avg =