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


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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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 9 years and a teacher from the past 16 years. He teaches Spoken English, Written English, Grammar and Vocabulary at Englishtan.