PASCO WA-9899 Ripple Tank System - Manual (Page 13)

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M o d e l N o . W A - 9 8 9 9 E x p e r i m e n t 1 : R e f l e c t i o n
13
Part 2: Reflection Using a Curved Barrier
Procedure
1. Replace the straight barrier with
the curved barrier and position
the curved barrier so it is aligned
‘parallel’ to the plane wave dip-
per as shown in Figure 1.3.
2. Turn on the light source. Trace
the position of the curved barrier
on the paper below the ripple
tank.
3. Turn on the ripple generator.
4. Mark the position on the paper
where the waves that reflect from
the curved barrier appear to con-
verge. Turn off the ripple genera-
tor.
5. Use the pipette to drop a single droplet of water at the position in the ripple tank
where the waves converged. Describe the shape of the waves that reflect from the
curved barrier.
Data Analysis
1. Use a drawing compass to complete the traced circular shape of the curved bar-
rier. Mark the center of the circle and measure the radius.
Question
1. What is the shape of the wave fronts that reflect from the curved barrier when
you dropped the droplet of water into the ripple tank?
2. How is the radius of the circle related to the distance between the curved barrier
and the point where the reflected plane waves from the plane wave dipper
appeared to converge?
Extension
Turn the curved barrier around by 180 degrees so that it
‘curves away’ from the plane wave barrier as shown in
Figure 1.4. Repeat the procedure as before, but trace
the shape of the reflected waves as well as the outline
of the curved barrier.
After sketching the reflected waves, draw at least three
rays perpendicular to the reflected waves. Extend the
rays until they intersect and mark the point of intersec-
tion. Measure the distance from the outline of the
curved barrier to the point of intersection, and compare
this distance to the radius of the traced circular shape of
the curved barrier.
Figure 1.3: Position of Curved Barrier
Figure 1.4: Reverse the Curved Barrier