Demonstration of Standing Waves using a Spring

# Materials Required

• Spring (Thick) of length 6 to 7 meter and 3 to 4 m
• Door handle
• Frequency generator
• Oscillator (Vibration generator)

# The Procedure

## Real Lab Procedure

### Spring with rigid ends

• Take a thick spring of length 6 to 7m.
• Tie one end to the handle of the door.
• Connect another edge of the spring to the oscillator.
• Connect frequency generator to oscillator.
• Power on the frequency generator.
• Change frequency to get the first harmonic.
• Note down the frequency. Calculate the corresponding time period.
• Change frequency to get second harmonics.
• Note down the frequency. Calculate the corresponding time period.
• Change frequency to get third harmonics.
• Find how the time period of higher harmonics is related to fundamental harmonics.

### Spring without rigid ends

• Take a thick spring of length 3 to 4m.
• Tie one end to the thread.
• Tie the thread to the handle of the door.
• Connect another edge of the spring to the oscillator.
• Connect the frequency generator to the oscillator.
• Power on the frequency generator.
• Change frequency to get the first harmonic.
• Note down the frequency. Calculate the corresponding time period.
• Change frequency to get the third harmonic.
• Note down the frequency. Calculate the corresponding time period.
• Change frequency to get the fifth harmonic.
• Find how the time period of higher harmonics is related to fundamental harmonics.

## Simulator Procedure

• Select the method.
• Select the length of the spring.
• Select the velocity of the sound wave.
• Click on the Start button.
• Click on the Next button and observe the different harmonics of corresponding methods.
• Observe how the time period changes for different harmonics.
• Click on the Reset button to redo the experiment with another method.

# Observation

 Sl.No Number of harmonics (n) Frequency (𝛎)         (Hz) Time Period (T)            (s)

# Conclusion

• When both ends of spring are rigid

The ratio of the time period of higher harmonic (Tn) to fundamental (T1) harmonic is 1/n.

• When one end of spring is not rigid

The ratio of the time period of higher harmonic (Tn) to fundamental (T1) harmonic is 1/n.