Question

Q-1: (a Briefly describe () Event,(i) Inertial Frame, (i) Proper Length (b) Define briefly the Doppler Effect for waves/periodic phenomena and explain why there are four different equations for sound waves but for light (or other electromagnetic waves) there are only two? (c) (i) Roughly Sketch World-line of a Space-ship moving with a constant speed say v-0. 2 C in an Inertial Reference frame that is stationary. (ii) Also sketch S' i.e. treat space as Inertial reference frame moving with a constant velocity v-0.2c,) Show world-line of two light signals, one Green, and one Red in both frames.

Answer 1

Doppler Effect: - Doppler Effect is the change in frequency of a wave for an observer moving relative to a source. For example a Car is moving towards an observer blows turn then frequency heard by observer is more. If car is moving away then frequency is less. This Effect of change of frequency is called Doppler Effect. For sound waves, observed frequency is given by f = (V plusminus V_0/V plusminus V_s) f_0 V = Velocity of Sound in dis, f_0 = Frequency of source. V_0 = Velocity of Observer, V_s = Velocity of Source Case I: - When Observer is moving towards the Source \r\n f = (V + V_0/V) f_0 Case II: - When observer is moving away from source f = (V - V_0/V) f_0 Case III: - When source is moving towards observer f = (V/V - V_s) f_0 Case IV: - When source moving away from observer f = (V/V + V_s) f_0