One person moves towards a stationary source of sound with a speed (1)/(5) times the speed of sound. Sound emitted from the source has wavelength lamdaand frequency f. Frequency and wavelength of sound heard by this person are respectively ......

One person moves towards a stationary source of sound with a speed (1)

1.	One person moves towards a stationary source of sound with a speed (1)/(5) times the speed of sound. Sound emitted from the source has wavelength lamdaand frequency f. Frequency and wavelength of sound heard by this person are respectively ......
Answer» `0.8f,0.8 LAMDA` `1.2 F, 1.2 lamda` `1.2 f, lamda` `f, 1.2 lamda` SOLUTION : We have, `(f _(L))/( v + v _(L)) = (f _(S))/( v + v _(S))` `therefore (f _(L))/( v + (v)/(5)) = (f _(S))/( jv + 0)` `therefore (f_(L))/( (6v)/( 5)) = (f)/(v)` `therefore f _(L) = (6)/(5) f = 1.2 f` Here, velocity of sound wave w.r.t. listener is, `v = v _(L) = v + (v)/(5) = (6v)/(5) = 1.2v` Frequency of sound wave heard by listener is, `f _(L)1.2f` Now, if wavelength of sound wave heard by the person is `lamda _(L)` then, `v = v _(L) = f _(L) lamda _(L)` `thereforef 1.2 v = 1.2 f xx lamda _(L)` `therefore lamda _(L) = (v)/(f)` `therefore lamda _(L) = lamda ""(because v = f lamda)`