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    Question

    What happens to resistance of a wire when its length is

    doubled (keeping area constant)?  
    A Doubled Correct Answer Incorrect Answer
    B Halved Correct Answer Incorrect Answer
    C Quadrupled Correct Answer Incorrect Answer
    D Same Correct Answer Incorrect Answer

    Solution

    Resistance R∝L, as per the formula R = ρ (L/A). So, if length becomes twice and cross sectional area stays same, resistance becomes 2R.   This relationship is critical in designing electric circuits and wires.   It also helps explain how electric heaters work.

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