JEE Main 201912 Apr, Evening shiftPhysicsEasyOscillations and Waves185× since 2002
A tuning fork of frequency 480 Hz is used in an experiment for measuring speed of sound (v) in air
by resonance tube method. Resonance is observed to occur at two successive lengths of the air column,
l₁ = 30 cm and l₂ = 70 cm. Then, v is equal to -