question_answer

A sonometer wire of length 114 cm is fixed at both the ends. Where should the two bridges be placed so as to divide the wire into three segments whose fundamental frequencies are in the ratio 1 : 3 : 4?     [JEE ONLINE 23-04-2013]

A)  At 36 cm and 84 cm from one end

B)       At 24 cm and 72 cm from one end

C)       At 48 cm and 96 cm form one end

D)       At 72 cm and 96 cm from one end

Correct Answer: D

Solution :

[d] Total length of the wire, L =114 cm

1: 3 :4

Let and be the lengths of the three parts As

and

Hence the bridges should be placed at 72 cm and 72 + 24 =96 cm from one end.