A source of sound emits sound waves at frequency f₀ . It is moving towards an observer with fixed speed v_s (v_s < v . , where v is the speed of sound in air.) If the observers were to move towards the source with speed v₀ , one of the following two graphs (A and B) will give the correct variation of the frequency f heard by the observer as v₀ is changed. The variation of f with v₀ is given correctly by

Step-by-step solution

According to Doppler's effect, the apparent frequency of sound when both source and observer are moving towards each other array ll & f= (v+v₀ ) f₀ (v-v₀ ) & f= ( v v-v_s ) f₀+ ( v₀ v-v_s ) f₀ array f= ( f₀ v-v_s ) v₀+ ( f₀ v-v_s ) v Equation of straight line, y=m x+c which is equation of straight line making an intercept c on Y -axis, Slope of the graph = f₀ v-v_s and intercept = v f₀ ^ v-v_s This condition is represented in graph A plotted between f and v₀ . Hence, option (c) is correct.