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The rheostat and the brightness of the bulbs

  1. Jun 10, 2017 #1
    1. The problem statement, all variables and given/known data
    In the circuit shown in the figure, what will happen to the brightness of bulb A and bulb B when the wiper moves from point X to point Y?

    2. Relevant equations

    3. The attempt at a solution

    When the wiper moves towards Y we get smaller resistance, hence the current intensity rises, so the brightness of A increases.
    I think the brightness of B will increase too, as the current passing in its branch will increase.

    I am not sure about my answer, what's your opinion?
  2. jcsd
  3. Jun 10, 2017 #2


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    Homework Helper
    Gold Member

    I agree with your answer.
  4. Jun 10, 2017 #3
    I have just found that my book provides the answer, it is: brightness of bulb A decreases and the brightness of bulb B doesn't change, but there is no explanation.
  5. Jun 10, 2017 #4


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    Homework Helper
    Gold Member

    That's wrong.
    Maybe this is the answer to some other similar question and the book just printed it at the wrong place.
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