H C Verma Solutions for Chapter: Light Waves, Exercise 1: QUESTIONS FOR SHORT ANSWER

If we put a cardboard (say $20 \mathrm{cm}\times 20 \mathrm{cm}$ ) between a light source and our eyes, we cannot see the light. But, when we put the same cardboard between a sound source and our ear, we hear the sound almost clearly. Explain.

TV signals broadcasted by Delhi studio cannot be directly received at Patna which is about $1000 \mathrm{km}$ away. But, the same signal goes some $36000 \mathrm{km}$ away to a satellite, gets reflected and is then received at Patna. Explain.

Can we perform Young's double slit experiment with sound waves? To get a reasonable fringe pattern, what should be the order of separation between the slits? How can the bright fringes and the dark fringes be detected in this case?

Is it necessary to have two waves of equal intensity to study interference pattern? Will there be an effect on clarity if the waves have unequal intensity?

Can we conclude from the interference phenomenon whether light is a transverse wave or a longitudinal wave?

Why do we not have interference when two candles are placed close to each other and the intensity is seen at a distant screen? What happens if the candles are replaced by laser sources?

If the separation between the slits, in a Young's double slit experiment, is increased, what happens to the fringe-width? If the separation is increased too much, will the fringe pattern remain detectable?

Suppose white light falls on a double slit, but one slit is covered by a violet filter (allowing $\mathrm{\lambda }=400 \mathrm{nm}$). Describe the nature of the fringe pattern observed.