Q. Assertion Static crashes are heard on radio, when lightning flash occurs in the sky.
Reason Electromagnetic waves having frequency of radio wave range, interfere with radio waves.

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Solution:

We know that lightening flash produces electromagnetic waves. Flash counts of hapahazard electricals fields and current oscillate between group of clouds. Here, many changes oscillate and produce electromagnetic waves. Hence, the electromagnetic waves which have frequencies of radio wave range interfere with radio waves which produces static crashes.