Consider the Doppler effect in two cases. In the first case, an observer moves towards a stationary source of sound with a speed of 50 ~m / s . In the second case, the observer is at rest and the source moves towards the observer with the same speed of 50 ~m / s . Then the frequency heard by the observer will be [velocity of sound in air =330 ~m / s .]

Step-by-step solution

For observer moving towards a stationary source, n ₁= n ₀ [ v + v _ L v ] For source moving towards a stationary observer, n ₂= n ₀ [ v v - v _ s ] Substituting the values for v, v_L and v_S in the equations above aligned & n ₁= n ₀ [ 330+50 330 ]=1.15 n ₀ & n ₂= n ₀ [ 330 330-50 ]=1.17 n ₀ & n ₂> n ₁ aligned The frequency heard will be more in the second case than in the first case.