Doppler Effect

Q.

We can hear the sound of the horn of an approaching car before the car reaches, because:

1. speed of sound is greater than car
2. high pitch of horn
3. low pitch of horn
4. no obstacle is present

Q.

It was a rainy day in Bangalore. Rohit was sitting beside the window when he saw lightning. He started his stopwatch. He found that after $22$ seconds of lightning its roaring was heard. Calculate the height of the clouds which caused this lightning. Given, speed of light = $3\times {10}^8$ $m{s}^{-1}$ and speed of sound = $340m{s}^{-1}$.

1. $7.5km$
2. $10km$
3. $5km$
4. $8.5km$