DAY 12 – DAW January

Simple Beats; Stationary waves in a string; Pulses and wave packets; Phase and group velocities; Reflection and Refraction from Huygens’ principle. motion, damped oscillation, forced oscillation and resonance;


Q 1. An observer on a railway platform observed that as a train passed through the station at 108 km/hr, the frequency of the whistle appeared to drop by 350 Hz. Find the frequency of the whistle. (Velocity of sound in air = 380 m/s) [10 marks]

Q 2. When two waves of nearly equal frequencies interfere, then show that the number of beats produced per second is equal to the difference of their frequencies. [10 marks]

Video Solution at 11 pm