Demonstration of Standing Waves using a Spring

Materials Required 

  • Spring (Thick) of length 6 to 7 meter and 3 to 4 m 
  • Thread 
  • 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.