MCQ
A tuning fork sounded together with a tuning fork of frequency $256$ emits two beats. On loading the tuning fork of frequency $256,$ the number of beats heard are $1$ per second. The frequency of tuning fork is
- A$257$
- B$258$
- C$256$
- ✓$254$
✓
Answer
Correct option: D.
$254$
d
(d) $n_A $= Known frequency $= 256,$ $n_B = ?$
(d) $n_A $= Known frequency $= 256,$ $n_B = ?$
$x = 2\, bps,$ which is decreasing after loading (i.e. $x\, \downarrow$) known tuning fork is loaded so $n_A \,\downarrow$
Hence $n_A\downarrow -n_B = x\downarrow$ ... $(i)$ $\rightarrow $ Correct
$n_B -n_A \downarrow= x\downarrow$ ... $(ii)$ $\rightarrow $ Wrong
==> $n_B = n_A -x = 256 -2 = 254 Hz.$
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