To determine the velocity of a pulse propagated through a stretched spring/slinky - Science Practicals

To determine the velocity of a pulse propagated through a stretched spring / slinky.

Wave motion: The transference of energy in a given medium due to oscillatory motion of the particles of that medium about the mean position is known as wave motion.
Pulse: A wave produced by a single disturbance in a given medium is known as pulse.
Slinky: A long flexible spring is called slinky.
Wavelength (λ): The distance covered by one complete rarefaction and one complete compression or distance between two consecutive compressions or rarefactions.
Frequency: The number of vibrations made by a particle in the slinky per unit time (one second) is called its frequency.
Materials Required
A flat wire coiled spring/slinky of copper, a metre rod, a stopwatch and a small wooden board or a hard bound book.

For Transverse Wave
Step 1: Take a slinky and place it lengthwise on the smooth surface of the table.
Step 2: Tie one end of the slinky with the fixed hook.
Step 3: Hold the free end of the slinky and stretch it (1 to 3 m depending upon the nature of slinky).
Step 4: Move your hand periodically and uniformly at right angles to the length of the slinky.
Step 5: Observe the  propagation of the wave through the slinky and observe  the formation of crests and troughs.

For Longitudinal Wave
Step 1: Compress the free end of the slinky periodically and observe the slinky.
Step 2: Measure the wavelength by measuring the distance between two consecutive troughs (T and T) or two crests (C and C) in case of transverse wave. In case of longitudinal wave, λ is equal to distance between two consecutive compressions (C and C) or rarefactions (R and R).
Step 3: Note the time as pulse (wave) passes through slinky for a particular distance from which we can find out the velocity of the wave.

Velocity of pulse =    m/s
• For the same slinky, the velocity of pulse will increase if it is stretched more and vice versa.

1. The slinky should be a flat wire of copper.
2. Measure the distance between points A and B very accurately.
3. Do not stretch the slinky backward for more than 10 cm.
4. Give a very sharp push to generate pulse.
5. Make sure that you arrest push by a wooden block or a hard bound book, so that it does not overshoot point A.
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