Question

A tuning fork of frequency 340 s^–1 vibrates just above a cylindrical tube. Height of tube is 120 cm. If velocity of sound is 340 ms^–1, the least height in cm of water required for resonance is –

• A. 52
• B. 25
• C. 54
• D. 45

Answer 1

Answer: (A)

52

Answer 2

– $\frac { \mathrm { v } } { 4 \ell _ { 2 } }$ = 5

or $\left( \frac { 1 } { 50 } - \frac { 1 } { 51 } \right)$= 5

= $\frac { 5 \times 50 \times 51 } { 1 }$

Ž n₁ = = $\frac { 5 \times 50 \times 51 } { 50 }$= 255 Hz

Ž n₂ = = $\frac { 5 \times 50 \times 51 } { 51 }$ = 250 Hz