Question

A source and an observer approach each other with same velocity 50m/s.  If the apparent frequency is 435sec^-1, then the real frequency is

A) 320 sec^-1

B) 360 sec^-1

C) 390 sec^-1

D) 420 sec^-1

Answer 1

A) 320 sec^-1

n' = n(v+v_o/v-v_s) n

⇒ 400 = n(360 + 40/360 - 40)

⇒ n = 320cps