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5 beats/second are heard when a turning fork is sounded with a sonometer wire under tension, when the length of the sonometer wire is either 0.95 m or 1 m. The frequency of the fork will be -

1. 195 Hz
2. 251 Hz
3. 150 Hz
4. 300 Hz

Correct answer: 195 Hz

Solution

The frequency of the tuning fork can be determined using the relationship between the beats heard and the frequencies of the two sound sources. Since 5 beats per second indicate a difference of 5 Hz between the fork and the wire's fundamental frequency, and the wire's frequencies for the given lengths are close to 200 Hz, the correct frequency of the fork is 195 Hz.

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