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    Question

    How does a bulb glow when the switch is turned

    on?
    A The filaments touch each other Correct Answer Incorrect Answer
    B The filaments expand Correct Answer Incorrect Answer
    C The filaments get heated up due to current and lights up Correct Answer Incorrect Answer
    D Current does not flow through circuit Correct Answer Incorrect Answer

    Solution

    The bulb glows because the filaments get heated up due to current and lights up. • The bulb work on the principle that when a metal is heated it starts emitting light at some point.is turned on • When the switch is turned, an electric current is passed through • When an electric current is passed through a conductor it generates heat, H = IR2t (Joule's equation), where I is the current, R is the resistance of the conductor and t is the time for which current is passed. • This heat is used by the atomic electrons to get excited to higher energy levels from the ground state. • When these electrons return back to their ground state, a light photon is emitted, and this is how a bulb glows.

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