Question

A resonance air column of length 20 cm resonates with a tuning fork of frequency 250 Hz. The speed of sound in air is

• A. 300 m/s
• B. 200 m/s
• C. 150 m/s
• D. 75 m/s

Answer 1

Answer: (B)

200 m/s

Length of air column $l=20cm=0.2m$

In resonance air column,
$\lambda =4l=4\times 0.2=0.8m$
Now, $\lambda =0.8m$ and $\nu =250Hz$
Hence, speed of sound in air $v=\nu \lambda =250\times 0.8=200m/s$