Question

Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen. Why?

Answer 1

Thunder is heard a few seconds after the flash is seen:

1. When we see the flash, it is actually the light energy travelling to our eyes, whereas thunder is the sound energy received by the ears.
2. The speed of light is $3\times {10}^{8}m/s$ and it does not depend on the medium.
3. But the speed of sound depends on the medium.
4. In air the speed of sound is around $334m/s$ which is much less than the speed of light.
5. Hence, light reaches the eyes faster than sound, and so flash is seen before the thunder is heard.