Question

In a resonance column experiment, the first resonance is obtained when the level of the water in the tube is at 20 cm from the open end. Resonance will also be obtained when the water level is at a distance of –

• A. 40 cm from the open end
• B. 60 cm from the open end
• C. 80 cm from the open end
• D. 100 cm from the open end

Answer 1

Answer: (B)

60 cm from the open end

Answer 2

n = $\frac { \mathrm { c } } { 4 \ell }$ , $\frac { \mathrm { dn } } { \mathrm { dt } } = \frac { \mathrm { c } } { 4 \ell ^ { 2 } } \left| \frac { \mathrm { d } \ell } { \mathrm { dt } } \right| = \frac { \mathrm { c } \mathrm { v } } { 4 \ell ^ { 2 } }$