Ripple Tank Review
Describe the Ripple Tank phenomena that are happening in each of the
pictures provided here. Marks for individual answers are given, however, the
questions are worth 3 marks each.
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A wave is propagating through water. (0.5)
Reflection of a wave from a barrier. (0.5)
Reflection of multiple straight wave from a
parabolic reflector. (1.0)
Straight waves reflect from parabolic reflector
in toward the focus of the parabola. (1.0)
The parabolic reflector is the “fix” or
correction for spherical aberration with a
straight wave reflecting from a circular barrier.
(1.0)
Circular waves created at the focus of the
parabolic reflector will reflect out as straight
waves. (1.0)
A wave is propagating through water. (0.5)
Reflection of a wave from a barrier. (0.5)
Reflection of multiple straight wave from a
straight reflector at an oblique angle. (1.0)
Interference is happening. (0.5)
Incident crests and/or troughs are interfering
constructively with reflected crests and/or
troughs making larger crests. (1.0)
Incident crests and/or troughs are interfering
destructively with reflected troughs and/or
crests, making a grey nodal area. (1.0)
The angle of incidence is equal to the angle of
reflection. 𝜃𝑖 = 𝜃𝑟 (1.0)
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A wave is propagating through water. (0.5)
Reflection of a wave from a barrier. (0.5)
Each point of reflection of the wave behaves
according to the law of reflection. 𝜃𝑖 = 𝜃𝑟
(1.0)
Reflection of a circular wave from a straight
barrier. (1.0)
The reflected wave behaves as if a “virtual
wave” was created on the other side of the
barrier. (1.0)
The actual wave source and the virtual wave
source are an equal distance from the
reflecting source and are on a line that is
perpendicular to the reflecting surface. (1.0)
A wave is propagating through water. (0.5)
Refraction of a wave. (0.5)
Refraction of a water wave is a change in
speed due to a change in medium (depth).
(1.0)
Water in the top left is deeper than that in the
bottom right of the ripple tank. This can be
detected because of the longer wavelength in
the top left. (1.0)
The speed of the waves in the top left are
faster than those in the bottom right, because
of the difference in depth. (1.0)
There is partial reflection at an oblique angle
of the waves in the top left portion and this
adheres to the law of reflection. 𝜃𝑖 = 𝜃𝑟 (1.0)
Incident crests and/or troughs are interfering
constructively with reflected crests and/or
troughs making larger crests. (1.0)
Incident crests and/or troughs are interfering
destructively with reflected troughs and/or
crests, making a grey nodal area. (1.0)
Circular waves are propagating through water.
(0.5)
Interference of two waves. (0.5
Crests interfere constructively with crests and
troughs interfere constructively with troughs in
a line called an anti-nodal line (1.0)
Crests’ constructive interference causes there
to be an even brighter line due to the larger
crest created. (0.5)
Troughs’ constructive interference causes
there to be an even darker line due to the larger
trough created. (0.5)
The line of destructive interference has crests
interfering destructively with troughs to make
a grey nodal area. (1.0)
The nodal line joins each of the nodal points.
(1.0)
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θi
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A wave is propagating through water. (0.5)
Reflection of a wave from an oblique barrier.
(1.0)
The angle of incidence is equal to the angle of
reflection. 𝜃𝑖 = 𝜃𝑟 . (1.0)
Diagram alterations (1.0)
θr
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(1.0)
Diffraction
A wave is propagating through water. (0.5)
Below are two diagrams depicting what
happens when individual molecules bump the
next particles the next ones and create small
wavelets. (1.0)
The wavelets interfere constructively to make
larger waves making crests that travel in the
water. (1.0)
The smaller the opening, the more obvious or
greater the diffraction. (1.0)