Question

A siren is fixed at the centre of a circle and an observer is performing a uniform circular motion around the siren with constant radius. The apparent frequency heard by the observer will be

• A. same as the actual frequency of siren.
• B. more than the actual frequency of siren.
• C. less than the actual frequency of siren.
• D. sometime more and sometime less than the actual frequency of siren.

Answer 1

The correct option is A same as the actual frequency of siren.

While moving on a circular path around the source, the velocity of the observer will always be perpendicular to the velocity of sound recived from the source i.e it is neither approaching nor receding from the source. Therefore, observer will hear same frequency as source is emitting.