## Due before class Wednesday, Jul 18th

Physics 106, Summer 2012

Did you complete the reading assignment?

Yes
No

Did you complete the entire quiz or spend at least 15 minutes working on this quiz and the attached links?
Yes
No

## KEY CONCEPTS:

1) Reflection is the part of a wave that returns to its original medium when it reaches a boundary between to media.

2) Refraction is the bending of a wave into a new medium caused by a change in wave velocity.

3) Light has wave properties allowing it to reflect and refract.

The following link shows light as it reflects and refracts at the boundary of two media: http://www.fisica.uniud.it/~deangeli/applets/Multimedia/Waves_java/Snell/propagation.html

The n2/n1 ratio you see is called the index of refraction, don't be too concerned about what the it means right now. Basically, it compares how fast light travels through the two media. The scroll bar at the top lets you change the value of the n2/n1 barrier and see the results from it. The other control is the black dot at the top where the initial light ray comes from. You can drag this black dot to change the angle the light hits the barrier at. Also note the angles θ1 (angle of incidence), θ2 (angle of reflection), and θ3 (angle of refraction) in the diagram at the bottom of the applet as the quiz will refer to these angle by those names.

Increase the angle of incidence by dragging the black dot to the left. How does increasing the angle of incidence affect the angle of reflection?

Increases
Decreases
Stays the same

Does increasing the angle of incidence increase or decrease the angle of refraction?

Increases
Decreases
Stays the same

Now change your option from the scroll box from 'Light from air to glass' to 'Light from air to water' which decreases your index of refraction. How does this affect the angle of reflection?

Increases
Decreases
Stays the same

How did it affect the angle of refraction?

Increases
Decreases
Stays the same

Move the black dot far to the right (but not all the way) and change the option from the scroll box to 'User defined ratio'. Now type in a ratio of 0.5 and hit enter. What happens to the speed of the refracted wave?

Speeds up
Slows down

What happens as you slowly move the black dot from the right to the left? Why does this happen?

Can the phenomenon you saw in the previous question occur when the index of refraction is greater than 1?

Now change the option in the scroll box to 'Same index of refraction'. Which wave property still seems to occur?

Reflection
Refraction
Neither

FEEDBACK

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Was there anything that you didn't understand in the reading assignment?  What was confusing to you?