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Physics Question - Series/parallel circuits

    • Thread Starter

    I have this question that I just can't figure out..
    This is it:
    "Consider two bulbs, X an Y, and a battery. The bulbs operate at the same voltage i.e. they light normally when each is connected to the battery. The bulbs are connected in series with the battery. Bulb X is brighter than bulb Y.
    The bulbs are now connectred in parallel with the battery.
    Which of the following statements is correct?:
    A.) Both bulbs have the same brightness
    B.) Bulb X is brighter
    C.) Bulb Y is brighter
    D.) Which bulb is brighter can't be determined without the battery voltage
    E.) Which bulb is brighter can't be determined without knowing current"

    Thank you!

    (Original post by llamaha)
    When the two bulbs are in series, think about why it would be brighter. It's power output is greater and you should know that P = IV. So, is I changing or is V changing? Using Ohm's law, what can you deduce about the resistance of the two bulbs?

    Now think about the two bulbs in parallel. How does the voltage and current change get distributed among the two bulbs? Remember P = IV and use the resistance values of the two bulbs.
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