Question

An observer is moving towards the stationary source of sound, then

• A. Apparent frequency will be less than the real frequency
• B. Apparent frequency will be greater than the real frequency
• C. Apparent frequency will be equal to real frequency
• D. Only the quality of sound will change

Answer 1

Answer: (B)

Apparent frequency will be greater than the real frequency

Answer 2

Apparent frequency in this case

$n' = \frac{n(v + v_{O})}{v}$

$\because$ $\frac{v + v_{0}}{v} > 1$ ⇒ $\frac{n'}{n} > 1$ i.e. $n' > n$.