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14.Waves and Sound
normal
When two tuning forks (fork $1$ and fork $2$ ) are sounded together, $4$ beats per second are heard. Now some tape is attached on the prong of the fork $2$. When the tuning forks are sounded again, $6$ beats per second are heard. If the frequency of fork $1$ is $200 \,Hz$, then the original frequency of fork $2$ is ........... $Hz$
A$204$
B$196$
C$202$
D$200$
Solution
(b)
Frequency of fork $1=200 \,Hz$
Frequency of fork $2=200 \pm 4$
When tape is added frequency of fork $2$ decreases.
When frequency of fork $2$ decreases number of beats increases.
Hence we know frequency of fork $2$ is
$f_2=200-4=196 \,Hz$
Frequency of fork $1=200 \,Hz$
Frequency of fork $2=200 \pm 4$
When tape is added frequency of fork $2$ decreases.
When frequency of fork $2$ decreases number of beats increases.
Hence we know frequency of fork $2$ is
$f_2=200-4=196 \,Hz$
Standard 11
Physics
