Physics Review Question
Unit: Waves
Year: 1996 Question#: 44
Question: The diagram below represents wave fronts traveling
from medium X into medium Y.
All points on any one wave front shown must be
(1 ) traveling with the same speed
(2 ) traveling in the same medium
(3 ) in phase
(4 ) superposed
What is this question really asking?
Explanation by: Sarah C.
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Answer 1
traveling with the same speed
INCORRECT
As seen in the diagram, the wave is in two different mediums. In this case
the points are not all traveling at the same speed. This is because when
a wave passes from one medium to another the bending which occurs (called
refraction) is caused by a change in speed of the wave upon entering a new
medium. return to top
Answer 2
traveling in the same medium
INCORRECT
As seen in the diagram, when the wave hits the boundary between the two
mediums, part of the wave enters first. Therefore all the points are not
traveling in the same medium all the time.
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Answer 3
in phase
CORRECT
The definition of a wave front is all points on a three- dementional wave
that are
IN PHASE with each other. Each line (front) represents the peak of the wave,
so the next line would represent the next peak.
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Answer 4
superposed
INCORRECT
Superposition is when two different waves occupy the same space or region
at the same time. This is on the contrary, this one wave is entering a different
medium.
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What's this question really asking?
This is asking if you understand what happens to a wave front when it enters
a medium. It also requires you to understand some words dealing with waves
and mediums. Especially what a wave front acts like. return
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