MCQ
Two strings $X$ and $Y$ of a sitar produce a beat frequency $4 Hz$. When the tension of the string $Y$ is slightly increased the beat frequency is found to be $2 Hz.$ If the frequency of $X$ is $300 Hz,$ then the original frequency of $Y$ was .... $Hz$
  • $296$
  • B
    $298$
  • C
    $302$
  • D
    $304$

Answer

Correct option: A.
$296$
a
(a) ${n_x} = 300Hz,$ ${n_y} = ?$ 

$x =$ beat frequency $= 4 Hz,$ which is decreasing $(4→2)$

after increasing the tension of the string $y. $

Also tension of wire $y$ increasing so ${n_y} \uparrow $   ($ \because n \propto \sqrt T$)

Hence ${n_x} - {n_y} \uparrow = x \downarrow $ $\rightarrow$ Correct 

${n_y} \uparrow - {n_x} = x \downarrow $ $\rightarrow$ Wrong 

==> ${n_y} = {n_x} - x = 300 - 4 = 296Hz$

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