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    • Thread Starter

    Ok, ac circuits are not in my syllabus, but I found this in an old Past Paper (of 1995), so JUST IN CASE the impossible happens, can someone please explain this to me.

    A mains circuit contains six similar bulbs connected in series. One of the bulbs has a broken filament. Voltmeter X and Y of infinite resistance are placed in the circuit as shown.

    What are the voltmeter readings in Volts?

    X Y
    A 0 0
    B 0 240
    C 40 40
    D 240 0

    Actually, it seems a bit interesting.
    Attached Images

    Its a potential divider. Most PD across most resistance. (Ac is irrelevant)

    A broken filament has an infinite resistance so gets all the PD

    Answer is 240v for X. 0v for Y
    • Thread Starter

    Oh Thanks

    Good thing I did not simply ignore it.

    My teacher said that no current flows so the no voltmeter would show any reading, but you are correct, I checked the answer in a solved paper.
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Updated: April 16, 2008

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