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

Answer  

The speed of light in air is 3 x 10 8 m/s.

The speed of sound in air is 340 m/s.

Since the speed of light is much more  as compared to the speed of sound in air, lightning travels faster than the thunder.

Hence, even though they occur at the same time, lightning is seen earlier than thunder can be heard.

  1. Class 9
  2. Chapter 12 Class 9 - Sound

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.