question_answer

When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats/s are heard. Now, some tape is attached on the prong of the fork 2. When the tuning forks are sounded again, 6 beats/s are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2?                     [AIEEE 2005]

A)  200 Hz                        

B)  202 Hz

C)  196 Hz            

D)       204 Hz

Correct Answer: C

Solution :

[c]

The frequency of foror 204 Hz Since, on attaching the tape on the prong of forits frequency decreases, but now the number of beats per second is 6 i.e., the frequency difference now increases.

It is possible only when before attaching the tape, the frequency of foris less than the frequency of tuning for. Hence, the frequency of foris 196 Hz.