Question

Choose the correct option in which there is NO perceived Doppler shift between a source and a detector of the sound .

• A. The source travels toward the stationary detector
• B. The detector travels toward the stationary source
• C. Both the source and the detector travel in the same direction
• D. Both the source and detector travel in opposite directions, with the source and detector moving away from each other
• E. Both the source and detector travel in opposite directions, with the source and detector moving toward each other

Answer 1

The correct option is C Both the source and the detector travel in the same direction

Doppler shifted frequency is given by

$f^{\prime }=f\left(\frac{c-v_o}{c-v_s}\right)$

When $v_o=v_s=v$,

$f^{\prime }=f\left(\frac{c-v}{c-v}\right)=f$

Thus there is no perceived Doppler shift when source and detector move in same direction with same speed.