Question

At a time when it is cloudy, there may be frequent thunder and lightning. The sound of thunder takes some time to reach you after you see the lightning. Can you answer why this happens? Measure this time interval using a digital wrist watch or a stop watch. Calculate the distance of the nearest point of lightning. (Speed of sound in air = 346 m s-1.)

Answer 1

because the speed of light in air is far more greater than that of sound.s
speed of light in air is 3*10^8m s-1

Answer 2

$\rm \:( i)This \: is \: because \: the \: speed \: of \: light \: is \: greater \: than \: the \: speed \: of \: sound.$

______________________________________

$\rm(ii)This \: time = 30s$

$\rm \ Speed \: of \: sound = 346m {s}^{ - 1}$

$\rm Distance = Speed \times time$

$\rm \qquad = 346 \times 30$

$\rm \qquad = 10380m$