Name ______________________
THE LAW OF REFRACTION
Background
As light travels from one medium to another, the path the light travels bends in a predictable fashion. This optical phenomena is known as refraction. The law of refraction can be used to determine the angle of refraction when the index of refraction is known for both mediums. The law of refraction is an important physical law with applications in the field of optics. The law of refraction is known as Snell’s Law, named for Willobrord Snell, who discovered the law in 1621.
Snell’s Law is written as follows
where
n1 is the index of refraction for the first medium
n2 is the index of refraction for the second medium
is the angle of incident
is the angle of refraction
Purposes
⦁ To explore the law of refraction.
⦁ To apply Snell’s Law to solve problems involving refraction.
Materials
⦁ The refraction simulation can be found ⦁ here. Click on the version labeled Intro.
Instructions
Setup the simulation as follows (these should be the default settings).
⦁ Select the option for Ray in the upper left side of the screen.
⦁ Select Normal in the lower left side of the screen.
⦁ Select Air for the top Material.
⦁ Select Water for the bottom Material.
⦁ Drag the Protractor and place it centered on the normal line (perpendicular dashed line) and the boundary line between the materials.
Your setup should look like the following image.
Part 1 – Light Passing from a Less Dense to a Denser Medium
In this part of the lab, you are going to investigate refraction as light goes from air to water. To this, you are going to adjust the angle of incidence for the incoming light and observe the effect it has on the angle of refraction. To activate the light, click on the red button. To adjust the angle of incidence, put your cursor on the light source and drag it in the direction of the green arrows.
For each of the scenarios below, set the angle of incident to the required angle and record the angle of refraction. Use these values, along with the index of refraction for both mediums, to verify Snell’s Law for each scenario.
Scenario 1:
Angle of Incidence
Air Index of Refraction
30o 1.00
Angle of Refraction
Water Index of Refraction
1.33
Scenario 2:
Angle of Incidence
Air Index of Refraction
60o 1.00
Angle of Refraction
Water Index of Refraction
1.33
Questions
⦁ In both scenarios, were you able to verify Snell’s Law?
⦁ Make a general statement comparing the angle of incidence to the angle of refraction as light moves from a less dense to a denser material.
⦁ Make a prediction regarding how the angle of incidence would compare to the angle of refraction if the light were moving from a dense to a less dense material.
Part 2 – Light Passing from a Dense to a Less Dense Medium
In this part of the lab, you are going to investigate refraction as light goes from water to air. To do this, change Material 1 to Water and change Material 2 to Air. For each of the scenarios below, set the angle of incident to the required angle and record the angle of refraction. Use these values, along with the index of refraction for both mediums, to verify Snell’s Law for each scenario.
Scenario 1:
Angle of Incidence
Water Index of Refraction
20o 1.33
Angle of Refraction
Air Index of Refraction
1.00
Scenario 2:
Angle of Incidence
Water Index of Refraction
45o 1.33
Angle of Refraction
Air Index of Refraction
1.00
Questions
⦁ In both scenarios, were you able to verify Snell’s Law?
⦁ Make a general statement comparing the angle of incidence to the angle of refraction as light moves from a dense material to a less dense material. Does this agree with your prediction in part 1?
⦁ Set the angle of incidence to 50o. What happens to the refracted ray at this and higher angles of incidence in this scenario?
Part 3 – Solving Problems with Snell’s Law
In this part of the lab, you are going to calculate the angle of refraction for two different scenarios, then verify the results of your calculation with the simulation.
⦁ Scenario 1: Material 1 is Air with an index of refraction of 1.00. Material 2 is glass with an index of refraction of 1.50. If the angle of incidence is 45 degrees, calculate the angle of refraction in the space provided below:
⦁ Setup the simulation to match the parameters of Scenario 1. Make a statement regarding whether or not your calculation agrees with the results of the simulation.
⦁ Scenario 2: Material 1 is Glass with an index of refraction of 1.50. Material 2 is water with an index of refraction of 1.33. If the angle of incidence is 55 degrees, calculate the angle of refraction in the space provided below:
⦁ Setup the simulation to match the parameters of Scenario 2. Make a statement regarding whether or not your calculation agrees with the results of the simulation.
