PASCO WA-9899 Ripple Tank System - Manual (Page 27)

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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 6 : W a v e S p e e d
27
Experiment 6: Wave Speed
Purpose
The purpose of this activity is to demonstrate the relationship of wave speed to fre-
quency (v = f
λ where v is the speed of propagation of the wave, f is the frequency,
and
λ is the wavelength) and wave speed to water depth.
Theory
For transverse waves, the wavelength is the distance from
one point on a wave to an identical point on the next wave,
such as the distance from one crest to the next crest. Fre-
quency is the number of waves per unit of time. Period, the
amount of time for one wave, is the reciprocal of frequency.
Since average speed is distance divided by time, wave speed
is wavelength divided by period, or wavelength multiplied
by frequency (the reciprocal of the period). See Figure 6.1.
Setup: Wave Speed
1. Mount the light source onto its rod at the back edge of the ripple tank.
2. Fill the ripple tank with a small amount to water and adjust the feet on the legs to
level the tank. Then add between 600 and 800 mL of water.
3. Use a rod and base to support the ripple generator and position the generator over
the midpoint of one side of the ripple tank.
4. Plug the light source into the ripple gen-
erator and connect the ripple generator
to its power adapter.
5. Connect the plane wave dipper to the
ripple arms. Adjust the ripple generator
until the bottom of the plane wave dip-
per is barely in contact with the surface
of the water. See Figure 6.2.
6. Place a sheet of paper directly under the
ripple tank so you will be able to mea-
sure the distances between wave fronts.
Equipment from Ripple Tank System
Ripple Tank Ripple Generator and Light Source
Plane Wave Dipper Ruler
Other Equipment and Materials
Large Rod Stand (ME-8735) Paper (about 40 cm by 40 cm)
90-cm Rod (ME-8738)
Figure 6.1: Wavelength
wavelength
Figure 6.2: Plane Wave Dipper
plane wave dipper