Q. A tuning fork arrangement (pair) produces $4\ beats/sec$ with one fork of frequency $288\ cps.$ A little wax is placed on the unknown fork and it then produces $2\ beats/sec.$ The frequency of the unknown fork is
A) $286\ cps$
B) $292\ cps$
C) $294\ cps$
D) $288\ cps$
Explanation
(b) $n_{A} =$ Known frequency $= 288\ cps,\ n_{B} = \ ?$
$x = 4\ bps,$ which is decreasing (from 4 to 2) after loading $i.e.\ x \downarrow$
Unknown fork is loaded so $n_{B} \downarrow$
Hence $n_{A} - n_{B} \downarrow = x \downarrow \ \ \ \rightarrow Wrong$
$n_{B} \downarrow - n_{A} \downarrow = x \downarrow \ \rightarrow Correct$
$\Rightarrow n_{B} = n_{A} + x = 288 + 4 = 292\ Hz$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.