23 Sec. 1-6
Did you complete the reading assignment?
Did you complete the entire quiz or spend at least 15
minutes working on this quiz and the attached links?
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:
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
Stays the same
Does increasing the angle of incidence increase or decrease the angle of
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?
How did it affect the angle of refraction?
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
happens to the speed of the refracted wave?
What happens as you slowly move the black dot from the right to the left? Why
does this happen?
Total reflection occurs. This is because the angle of refraction is greater than 90 degrees and a wave cannot refract into itself.
Can the phenomenon you saw in the previous question occur when the index of
is greater than 1?
No, the angle of refraction will never be greater than 90 degrees, so you will never have total reflection.
Now change the option in the scroll box to 'Same index of refraction'. Which
wave property still seems to occur?
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Was there anything that you didn't understand in the reading assignment?
What was confusing to you?