This video lecture from Waves (F.Sc. first year physics) This video explains the Doppler,s effect and you will learn about doppler,s effect , and its cases ,you will also learn about the relation of frequency and wavelength also you will that when a source is moving away and towards the observer then their is change in wavelength while speed of sound remains constant. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.