Question
State the expression for apparent frequency when source is stationary and listener is
$1)$ moving towards the source
$2)$ moving away from the source
$1)$ moving towards the source
$2)$ moving away from the source
✓
Answer
Let,
$n =$ actual frequency of the source.
$n_0 =$ apparent frequency of the source,
$v =$ velocity of sound in air.
$v_s $= velocity of the source.
$v_l =$ velocity of the listener.i. If listener is moving towards source then apparent frequency is given by,
$n = n _0\left(\frac{v+v_L}{v}\right)$ i.e., apparent frequency increases.
ii. If listener is receding away from source then apparent frequency is given by, $n = n _0\left(\frac{v-v_L}{v}\right)$ i.e., apparent frequency decreases.
$n =$ actual frequency of the source.
$n_0 =$ apparent frequency of the source,
$v =$ velocity of sound in air.
$v_s $= velocity of the source.
$v_l =$ velocity of the listener.i. If listener is moving towards source then apparent frequency is given by,
$n = n _0\left(\frac{v+v_L}{v}\right)$ i.e., apparent frequency increases.
ii. If listener is receding away from source then apparent frequency is given by, $n = n _0\left(\frac{v-v_L}{v}\right)$ i.e., apparent frequency decreases.
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