Change in wavelength, Sonic Boom and Mach Number

Lesson 18 of 21 • 3 upvotes • 9:19mins

Rajesh Kumar

Change in wavelength, Sonic Boom and Mach Number. Change in wavelength is observed when speed of source with respect to medium and observer consider in rest. then the Apparent frequency observe apparent frequency is equal to the speed of sound in air Plus speed of observer divided by speed of sound in air minus speed of source whole x natural frequency .new wavelength after solving these equations with speed of source is equal to U, we can calculate change in wavelength Lambda this is equal to speed of sound in air - speed of source ,divided by speed of sound in the ear hole X wavelength. difference between two maximum is change in wavelength. when lambda constant then concentric spherical wavefront created. when a speed of source is 'u' then no any concentric wavefront . all circles are different is wavefront having its centre at the position where the source is situated .preceeding wavefront will exceed the next one by an amount 'Vxt ' the spacing between the successive difference decrease along the direction of motion and increases on the opposite side. this separation being the new balance the change in wavelength due to the motion of the source . 'Sonic boom' subsonic velocities less than speed of sound in air. Supersonic velocities greater than a speed of sound in air. Supersonic plane travel in medium emmit cracking sound. known as sonic boom. a spherical wavefront intersect over the surface of a cone with the apex at the source. due to constructive interference of a large number of waves arriving at the same instant on the surface of the cone. pressure waves of a very large amplitude are sent with the conical wavefront. such waves are also called 'shock waves' . the ratio of speed of source and speed of sound in air is called ' Mach number when both the speed = then speed of source is called one Mach