Investigation of the variation of fundamental frequency of a stretched string with tension

Every object has a natural frequency of vibration. If kinetic energy is applied to an object at a rate that matches its natural frequency, resonance occurs and the object vibrates. In this experiment a small current, produced by a signal generator, causes the sonometer wire to move up and down due to interaction with the magnetic field of a U-shaped magnet. When the rate of movement due to the current matches the fundamental frequency of the wire, resonance occurs causing noticeable vibration. If the tension on the wire is increased (length kept constant), the resonant frequency of the wire also increases.

Canvas not supported; please update your browser.

  1. Press the "Signal ON" button.

  2. Adjust the frequency of the signal current using the right hand slider at the bottom.

  3. When maximum vibration occurs, press the "Signal OFF" button.

  4. Record the frequency of vibration of the wire (Hz) and the tension (N) in the Newton meter.

  5. Using the left hand slider change the tension in the wire.

  6. Repeat steps 1 to 6 until you have at least six sets of tension and frequency readings.

On graph paper, draw a graph of frequency against the square root of the tension(x-axis). Start both axes at zero.
A straight line graph through the origin shows that frequency is proportional to square root of tension.

Sound Experiments           All Physics Experiments