Question

Two tuning forks A and B vibrating simultaneously produce 5 beats. Frequency of B is 512. It is seen that if one arm of A is filed, then the number of beats increases. Frequency of A will be

• A. 502
• B. 507
• C. 517
• D. 522

Answer 1

The correct option is C

517

After filling frequency increases, so $n_A$

decreases $(\downarrow )$ . Also it is given that beat

frequency increases $(i.e.,x\uparrow )$

Hence $n_A\downarrow -n_B=x\uparrow$ .... (i) ------ correct

$n_B-n_A\uparrow =x\uparrow$ ....(ii) ------- Wrong

$\Rightarrow n_A=n_b+x=512+5=517Hz.$