Question

A tuning fork and an air column in resonance tube whose temperature is 51°C produces 4 beats in 1 second when sounded together. When the temperature of the air column decreases, the number of beats per second decreases. When the temperature remains 16°C, only 1 beat per second is produced. Then the frequency of the tuning fork is -

• A. 55 Hz
• B. 50 Hz
• C. 68 Hz
• D. None

Answer 1

Answer: (B)

50 Hz

Answer 2

v µ n $\propto \sqrt { \mathrm { T } }$ because l = constant

= $\sqrt { \frac { 324 } { 289 } }$ = $\frac { 18 } { 17 }$

17N + 68 = 18N + 18

50 = N