Physics
To measure the speed of an approaching car a police officer shines

Microwaves on it
Radio waves on it
Ultra high frequency waves on it
Light waves on it

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Physics
Lightning is produced when

Water vapour produces electricity in the clouds
Clouds strike against impurities in air and the friction burns up these impurities
Similar charges of electricity rush towards each other and then get repelled
Strong opposite charges in different clouds break down the resistance offered by the intervening air

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