JEE PYQ: Waves And Sound Question 24
Question 24 - 2019 (08 Apr Shift 1)
A wire of length 2L, is made by joining two wires A and B of same length but different radii $r$ and $2r$ and made of the same material. It is vibrating at a frequency such that the joint of the two wires forms a node. If the number of antinodes in wire A is $p$ and that in B is $q$ then the ratio $p : q$ is :
(1) 3 : 5
(2) 4 : 9
(3) 1 : 2
(4) 1 : 4
Show Answer
Answer: (3)
Solution
As there must be node at both ends and at the joint of the wire A and B so
$\frac{f_A}{f_B} = \sqrt{\frac{\mu_B}{\mu_A}} = \frac{r_B}{r_A} = 2 = \frac{\lambda_A}{\lambda_B}$
$\Rightarrow \lambda_A = 2\lambda_B \Rightarrow \frac{P}{q} = \frac{1}{2}$
BETA
