Physics
Quality of a musical note depends on

Velocity of sound in the medium
Harmonics present
Amplitude of the wave
Fundamental frequency

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Physics
Lightning is produced when

Strong opposite charges in different clouds break down the resistance offered by the intervening air
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

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Physics
Planets do not twinkle because

Their distance from the earth does not change with time
They emit light of a constant intensity
They are nearer to earth and hence we receive a greater amount of light.
They are very far away from the earth resulting in decrease in intensity of light

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