Two uniform stretched wires A and B made of steel are vibrating under the same tension. If the first overtone of A is equal to the second overtone of B and if the radius of A is twice that of B, the ratio olf the lengths of the strings is?
n is the number of overtone .
From the relation of the stretching of the of an wire with frequency and mass per unit length is given in the third step .
Here m is the mass per unit length .
The frequency is calculated using the equation,
L = resonating length.
T = tension at the string.
m = mass/unit length of the wire.
Derivation of the equation:
Laws of transverse vibrations of stretched strings;
Law of length:
For a given string under constant tension, the frequency of vibration is inversely proportional to the length of the string.
Law of tension:
For a given string of constant length, the frequency of vibration is directly proportional to the square root of the tension.
Law of mass:
For a string of constant length and under a constant tension, the frequency of vibration is inversely proportional to the square root of its mass per unit length. If M is the mass and L is the length of the string then;
If d is the diameter of the wire then;
Substituting in equation (1) we get;
The law of mass may be put into two additional laws, for strings of circular cross-section, as given below.
Hope this helps you .