Gizmos Student Exploration: Refraction

Vocabulary​:​ angle of incidence, angle of refraction, frequency, index of refraction, medium, refraction, Snell’s law, total internal reflection, wave front, wavelength, wave speed

Prior Knowledge Questions ​(Do these BEFORE using the Gizmo​.) Two runners ran side by side, each holding one end of a horizontal pole.

1.What would most likely happen if one of the runners began jogging in knee-deep water?

The jogger would slow down because when one of your body parts are under water they are slower the water basically pulls your body down just like the jogger if he was in the water.

2.How would this affect the direction of the runners? Explain. ​For me whenever I run in the water I really dont move directions it depends on the wave the waves can be moving my body and I dont knotice it.

Gizmo Warm-up Light can travel through many materials, or ​media​. As with a runner on pavement or sand, the speed of light can change when it moves into a different medium. The ​Refraction Gizmo™ allows you to observe what happens to a beam of light as it travels from one medium to another.

Turn off ​View wave fronts​. Set ​Index of refraction​ ​2​ to 3.0.

1.Click ​Play​ (). Observe the ray of light as it passes from ​Medium 1​ to ​Medium 2​.

A.What happens to the speed of the light wave? ​The speed of the light slowed down because it had to go to another angle.B.What happens to the direction of the light wave? ​It changes direction when it hits the line.

The bending of the light ray you see is called ​refraction​.

2.Click ​Reset​ () and turn on ​View wave fronts​. A ​wave front​ is an imaginary line that connects the crests or troughs of a wave. The ​wavelength​ of a wave is the distance between wave fronts.

Click ​Play​. What happens to the wavelength of the wave as it passes into ​Medium 2​?When the wavelegnth passes medium 2 it slows down to change direction/angle its going.

Activity A:

Angle of refraction

Get the Gizmo ready​:

●Click ​Reset​. Turn off ​View wave fronts​.●Make sure ​View normal​ is selected.●Make sure ​Index of refraction​ ​1​ is 1.0 and ​Angle of incidence ​is 45°.●Set ​Index of refraction 2​ to 2.0.

Introduction: ​The normal is an imaginary line perpendicular to the boundary between two media. The ​angle of incidence​ is the angle between the light ray in medium 1 and the normal.The ​angle of refraction​ is the angle between the ray in medium 2 and the normal.

Question: What affects how much light waves refract?

1.Measure​: Click ​Play​. To measure the angle of refraction, turn on ​Click to measure angles​. Drag the protractor’s vertex to the intersection of the ray and the normal. Align the protractor’s legs to the ray and the normal in Medium 2​.

What is the angle of refraction?​ 33.05

2.Gather data​: For each angle of incidence listed in the table below, use the Gizmo to find the angle of refraction. Then, fill in the “Change of direction” column by subtracting the angle of refraction from the angle of incidence.

Angle of incidence Angle of refraction Change in direction

20° 19.49 31.94

40° 39.96 40.61

60° 60.81 60.47

80° 81.67 98.22

3.Analyze​: What patterns do you notice? ​The measurments would get gigher everytime you change it to a different direction.

4.Explain​: Do you think refraction would occur if the angle of incidence is 0°? Explain.No because it wont beableto move without an angle.

5.Predict​: The ​index of refraction​ indicates how fast light can travel through a medium. The higher the index is for a medium, the slower light will travel through that medium. How do you think increasing a medium’s index of refraction might affect the angle of refraction?

It can change the angle of the light if you changethe medium.

6.Gather data​: Keep the ​Index of refraction 1​ set to 1.0. Set the ​Angle of incidence​ to 60°.For each ​Index of refraction 2​ listed in the table below, use the Gizmo to find the angle of refraction​ ​and the change in direction.

Index of refraction 2 Angle of refraction Change in direction

1.0 44.0 63.9

2.0 66.3 70.6

3.0 75.9 80.3

7.Analyze​: What patterns do you notice? ​The number increases when you change the direction.

8.Explain​: Why does no refraction occur when the media have the same index of refraction?We have learned that refraction occurs as light passes across the boundary between  two media. 

9.Explore​: Set the ​Index of refraction 2​ to 1.0. Set the ​Angle of incidence​ to 25°. Collect data for each ​Index of refraction 1​ listed in the table below.

Index of refraction 1 Angle of refraction Change in direction

1.5 2.0 2.24

2.0 3.45 4.00

3.0 4.50 4.98

10.Analyze​: What did you notice about the change in direction in the first two trials? What happened in the third trial? When the angle of refraction is greater than 90°, the beam of light will reflect off of the surface instead of refracting through the surface. This is called ​total internal reflection​.The trials change when you change the angle because it has toslow down to goto a different direction