Wb-6 The Monochord (The Sonometer)

Aim

To demonstrate the fundamental law of vibration of a stretched string.

Apparatus

  • The monochord
  • Set of attached weights
  • Frequency meter if required

Sonometer 1 Sonometer 2

The Monochord Equation

Monochord Apparatus and Equation.

Description

The monochord consists of a sounding box which supports a wire whose length of vibration may be adjusted by the movable bridge B. The tension is adjustable by the weights D. The equation for the vibration of a stretched string may be verified .

The equation above shows that:

for a string under constant tension the frequency varies inversely as the length;for a string of constant length the frequency is proportional to the square root of the tension;for a given length and constant tension the frequency varies inversely as the square root of the mass/unit length.

which are Mersenne's laws.

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