Question

A glass tube of 10 m length is filled with water. The water can be drained out slowly at the bottom of the tube. If a vibrating tuning fork of frequency 500 Hz is brought at the upper end of the tube and the velocity of sound is 330 m/sec. Then how many resonance can be obtained?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (C)

3

Answer 2

First = $\frac { \lambda } { 4 }$ = $\frac { 1 } { 4 } \left( \frac { \mathrm { v } } { \mathrm { n } } \right)$ = $\frac { 1 } { 4 } \times \frac { 330 } { 500 }$ = 0.165 cm

Second = $\frac { 3 \lambda } { 4 }$ = 3 × 0.165 = 0.495 cm

Third = $\frac { 5 \lambda } { 4 }$ = 5 × 0.165 = 0.825 cm

Fourth = $\frac { 7 \lambda } { 4 }$ is not possible.