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
Strong opposite charges in different clouds break down the resistance offered by the intervening air
Similar charges of electricity rush towards each other and then get repelled

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Physics
A man standing at the top of a tower has two spheres A and B. He drops sphere A downwards and throws sphere B horizontally at the same time. Which of the following is correct ?

Both the spheres will reach the ground simultaneously.
A will reach the ground first.
The question is incomplete because the masses of the spheres are not given.
B will reach the ground first.

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Physics
Circuit breaker usually operate under

After D. C. component has ceased
Transient state of short-circuit current
Steady state of short-circuit current
Sub-transient state of short-circuit current

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