Bright Waves script
1. To investigate the relationship between waves
in a water tank and the bright and dark patterns
on the bottom.
2. Refraction: When a ray of light passes from a
less dense material into a more dense material,
it bends towards the normal.
3. A concave surface diverges light rays decreasing
the illumination in the region of the bottom
where the rays would otherwise have gone.
4. A convex surface converges light rays; the
region where the rays cross, and where the light
is therefore brighter, is called a caustic.
Depending on the shape of the water surface,
the caustic can be a point, a line or a threedimensional "surface." If the bottom of the pool
happens to intercept the caustic, you see a
bright point or line on the bottom. If the bottom
intercepts the rays either before or after they
cross, it is illuminated somewhat, but not as
brightly as it would be at the caustic.
5. pic
6. Materials
7. We Identified possible hazards and monitor
them through the experiment.
8. Set up the equipment – Fill up the clean tank to
2/3 full (we used …cm). Place the tank on an
elevated platform (we used…cm). Place a white
sheet beneath and at the back of the tank to
measure readings easier. Draw increment lines
on the glass to measure the amplitude of the
waves ( we used 5mm increments) Attach globe
and wave maker (we used a pine block attached
to a metal rod) to the retort stand. Plug in wires
from the globe to the 12DC power box. Place
video camera in a position where it can see the
waves the readings on the sheet below. Making
sure to keep the video camera at the same
height of the waves to avoid parallax error and
make it easier to read.
9. Explain the things in pic
10. Turn the power box on and turn the voltage up
to make the measurements easy to see (we used
12 volts). Press record on the video camera.
Move the wave maker up and down with the
rod to create the waves, trying to keep the
waves as alike as possible then after sufficient
data, Stop the recorder.
11. Video
12. Once the waves have settled and the water is
flat, repeat with different speeds and to vary the
period and amplitude trying to create waves
with high period and low amplitude to waves
with low period and high amplitude.
13. Repeat with lower light height
14. Repeat with lower water level
15. Results
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Convex waves –
Concave waves –
Lower light height
Lower light height
Lower water level
Analysis
These photos are showing the refraction of the
light going into the water at the different angles
created by the convex to concave waves.
35. When the wave has a higher amplitude and
shorter wavelength the light is brighter in one
centre spot.
When the wave has a lower amplitude and
longer wavelength the light is more spread out.
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41. Keeping Amplitudes and Wavelengths constant
and then changing variables
42. The relationship between waves in a water tank
and the bright and dark patterns on the bottom
is directly related to refraction of the water.
Whether the wave is concave or convex changes
the angle of the normal and changes how the
light refracts in the water which determines the
bright and dark spots on the bottom.
Convex waves = caustics respectively
Concave waves = Darker spots respectively