PASCO WA-9899 Ripple Tank System - Manual (Page 12)

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R i p p l e T a n k S y s t e m E x p e r i m e n t 1 : R e f l e c t i o n
12
Part 1: Reflection Using a Straight Barrier
Procedure
1. Arrange the long barrier in the middle of the tank so the barrier is at an angle to
the plane wave dipper (see Figure 1.2).
2. Turn on the ripple generator and
the light source. Set the light
source to ‘STROBE’. Set the rip-
ple generator frequency to 20 Hz.
Set the amplitude to slightly less
than half of maximum.
3. On the paper below the tank, place
the ruler parallel to the plane
waves that are incoming to the
barrier. Make a line to show the
incoming wave front.
4. Place the ruler parallel with a
reflected wave and again make a
line to show the outgoing
(reflected) wave front.
5. Trace the position of the straight barrier.
6. Turn off the ripple generator and light source.
Data Analysis
1. Draw a line that is perpendicular to the incoming wave front and extend the line
to the outline of the straight barrier. This represents the incoming ray, so draw an
arrow on it pointing to the barrier.
2. Draw a line from the point where the incoming ray intersects the straight barrier
so it crosses the reflected wave front at a right angle. This represents the reflected
ray, so draw an arrow on it pointing away from the barrier.
3. Draw the normal (perpendicular) line at the point of reflection on the outline of
the straight barrier.
4. Measure the angle of incidence and the angle of reflection and record the mea-
surements in the table.
5. Repeat the procedure with the barrier at a different angle.
Question
1. What is the relationship of the angle of incidence and the angle of reflection?
Table 1.1: Reflection Results
Trial #1 Trial #2
Angle of Incidence
Angle of Reflection
Figure 1.2: Position of Straight Barrier
Tip: Adjust the
amplitude as
necessary to
make a clear
pattern of plane
waves.