Question

The frequencies of three tuning forks A, B and C have a relation $n_A>n_B>n_c$. When the forks A and B are sounded together the number of beats produced is n${}_1$. When A and C are sounded together the number of beats produced is n${}_2$, then the number of beats produced when B and C are sounded together is

• A. $n_J+n_2$
• B. $\frac{n_1+n_2}{2}$
• C. $n_2-n_1$
• D. $n_1-n_2$

Answer 1

Answer: (C)

$n_2-n_1$

No. of beats produced, $n=n_1-n_2$
When A and B are sounded, $n_1=n_A-n_B$
When A and C are sounded, $n_2=n_A-n_C$
When B and C are sounded:

$n=n_B-n_C$
$=(n_A-n_C)-(n_A-n_B)$
$=n_2-n_1$