Question

A thunder is heard 4 seconds after the lightning. At what distance, the lightning occurred?
(A)$1480m$
(B)$1380m$
(C)$2380m$
(D)$1000m$

Answer 1

Hint:Thunder and lightning are generally produced simultaneously, as in this question given. Sound of thunder and lightning are both types of waves. Speed of the wave generally depends on the medium through which it transfers.

Formula used:
$s = \dfrac{d}{t}$ where, $s$ is speed of particle travelled distance $d$ in time$t$.

Complete step by step answer:
Sound wave and light wave:
Sound waves and water waves are examples of mechanical waves. Light wave is not considered as an example of mechanical wave, because it does not involve motion of matter. Mechanical waves involve motion of matter. So, mechanical waves require a medium to propagate. Light wave is a type of electromagnetic wave in which electric fields and magnetic fields are perpendicular to each other. Electromagnetic waves do not require a medium to propagate.Speed of the wave depends on a medium of propagation also. Sound through air can travel easily, but faces difficulty to travel through denser medium like water or wall. Sound waves cannot travel through space as it requires medium to transfer energy for propagation. Speed of sound in air is about $343m{s^{ - 1}}$ .
To calculate distance between place of origin of thunder and recipient of thunder’s sound, we have been given the time required by thunder to be heard is $t = 4s$. By putting value of $t$ in equation of speed we get,
$s = \dfrac{d}{t}$
To find out distance using speed and time,
$d = s \times t$
By putting speed of sound $343m{s^{ - 1}}$ and $t = 4s$ we get,
$d = 343 \times 4m$
$\therefore d = 1372m$ which is nearer to $1380m$ .

Hence, option (B) is the correct option.

Note: Lightning is electric discharge that produces due to electrical imbalance between two clouds or clouds and ground. It tries to make equilibrium between two charged bodies. It is similar to spark occurs due to potential difference, but energy of lightning is in gigajoules.