The source is emitting sound of frequency 'n'. A source and a listener both are moving towards each other with a speed equal to ( V 3 ) , where V is the speed of sound. The frequency heard by the listener will be

Step-by-step solution

The apparent frequency heard by the listener is given by the Doppler effect formula: n' = n ( V + v_L V - v_S ) Since both the source and the listener are moving towards each other with speed V 3 : v_L = V 3 v_S = V 3 Substituting these values into the formula: n' = n ( V + V 3 V - V 3 ) n' = n ( 4V 3 2V 3 ) n' = 2n Answer: 2n