WAVE PROPERTIES LAB
The wave characteristics you will observe in this lab are common to all waves (light
sound water)
You will work in the hall – parallel and very close to the lockers. First do the fill-ins
below:
A wave is a disturbance which can move through space or through a material.
_______________waves travel through matter. _______________waves can also travel
through a vacuum.
Procedure:
Take your slinky into the hall. THE SLINKY MUST NEVER LEAVE THE FLOOR!!!
1. Practice sending single pulses down the spring by snapping your wrist sharply, moving
the spring quickly from the center to one side and back to the center. The pulse moves
down the length of the slinky. Watch the string tied to one coil of the spring. It moves
(perpendicular or parallel) to the direction the pulse moves.
2.Now send a pulse by quickly pushing the spring forward and pulling it back. Watch the
motion of the string. It moves (perpendicular or parallel) to the direction the pulse moves.
3. Send a tall pulse followed by a small one. Does one pulse catch up to the
other?_________
4. Generate a single pulse in the spring keeping the stretch of the spring constant. Use a
stopwatch to time the journey of the pulse from one end to the other and aback again.
Perform three trial and report the average time to the nearest 0.1 s.
Trial 1__________trial 2___________trial 3_________ average time__________
5. Without changing your position on the floor ( we don’t want to change the distance the
pulse travels) pull the slinky tighter gather up about ¼ of the coils in your hand. Time the
journey of the pulse down and back as in step 4
Trial 1__________trial 2___________trial 3_________ average time__________
6. Shake the spring back and forth steadily to produce a traveling wave while your
partner holds the other end still. The frequency of the wave depends on how fast you
shake the spring. Shake the spring slowly. Draw the wave, using the dotted line as the
equilibrium position.
If the line represents one second what is the
Frequency_____________
Period_____________
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Now shake the spring more rapidly, increasing the frequency. Draw the wave again, show
the difference in appearance.
If the line represents one second what is the
Frequency_____________
Period_____________
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7. both partners should practice sending single pulses toward each other at the same time.
Send the pulse on on the same side of the spring. Watch the pulses when they meet.
When pulses on the same side of the slinky meet, for an instant their displacements from
the equilibrium position ( add up or cancel out ) to make a( shorter or taller) pulse.
8. Send the pulses on opposite side of the spring. Watch the pulses when they meet. For
an instant their displacements from the equilibrium position ( add up or cancel out) this
happens very quickly!
9. Have one partner hold one end of the slinky very tightly against a book. The other
partner should send a single tall pulse down the slinky. Watch the pulse closely as it hits
the book and turns back the returning pulse ( stays on the same side or swaps sides) of the
slinky.
10. Loop the long string though a coil on the end of the slinky and hold the very ends of
the double string. Your partner should send a single tall pulse down the slinky. Watch
the pulse closely as it turns back. The returning pulse (stays on the same side or swaps
sides) of the slinky.
11. connect the slinky with the smaller tightly coiled spring by wisting the coils together.
Have one partner hold the end of the small spring while the other sends a single tall pulse.
Watch pulse as it crosses the boundary from one medium to the other. Which of these
happens?
__ all of the pulse turns back at the boundary and one goes through to the new medium.
__all of the pulse goes through to the new medium and none turns back
__part of the pulse goes through to the new medium and part turns back
12. Move close enough together tom make the pulse move slowly. Hold the opposite end
against a book Send a tall pulse down the slinky and watch the height of the pulse as it
travels back and forth through the medium the pulse ( gets taller or shorter or stays the
same)
Wave interference:
13. The result of the superposition of two waves when they meet is called
_____________. When the displacements are in the same direction ( crest meets crest as
in step 7)
__________ interference occurs and the displacements ( add up or cancel out)
When the displacements are in opposite directions ( crest meets trough as in step 8)
______________ interference occurs and the displacements ( add up or cancel out)
Turning back at a boundary:
14. The turning back of a wave at a boundary is called _________ in step 9 the pulse was
reflected from a rigid boundary which would not allow the slinky to move. When the
boundary is very rigid, the reflected pulse is ( erect or inverted ) which means that a crest
( stays crest or becomes a trough)
In step 10 the string’s boundary was flexible allowing the slinky to move. The reflected
pulse was ( erect or inverted ) which means that a crest ( stays crest or becomes a trough)
Going from one medium to another:
15. When a wave goes from one medium to another ( part or all) of the energy is
transmitted into the new medium and ( part or all) of the energy is reflected. The
amounts transmitted and reflected depend on the differences in the two media. When the
difference is small ( most or little )of the energy is transmitted.
Energy loss in a medium
16. As a tall pulse moves through a medium its amplitude ( increases or decreases). This
is called damping
Wave Properties Lab
Conclusions
Use your lab observations and your notes to answer these questions.
A. Types of mechanical waves.
In step 1 the particles of the medium moved ( perpendicular, parallel ) to the direction
the wave moved. This type of wave is a ______________wave. In a traveling wave, the
upward pulses are called _____________and the downward ones are called __________.
In Step 2, the particles of the medium moved ( perpendicular, parallel ) to the direction
the wave moved. This type of wave is a ____________wave.
B. Wave speed
In step 3, you made tall and short pulses. The maximum displacement from the
equilibrium position is called the ________________ of a wave. To make a tall pulse,
more ____________had to be done to the slinky. Therefore, waves with larger
____________ have more ______________.
You found that a short pulse ( did , did not) catch up to a tall one. Amplitude doesn’t
affect wave speed.
In step 5 you changed the medium by stretching the slinky tighter. What happened to the
speed of the pulse?____________.
The speed of a wave depends on the ( amplitude , type of medium).
Wavelength and Frequency
The ______________ of a wave is the number of complete vibrations per second. The
__________ of the wave is the distance the wave travels in one complete vibration.
Label one complete wavelength below.