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26 December, 19:42

Capacitors A and B are identical. Capacitor A is charged so it stores 4 J of energy and capacitor B is uncharged. The capacitors are then connected in parallel. The total stored energy in the capacitors is now:

A. 16 J

B. 8 J

C. 4 J

D. 2 J

E. 1 J

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Answers (1)
  1. 26 December, 20:27
    0
    B. 8 J

    Explanation:

    From the question,

    The voltage in each of the identical capacitor is given as

    W = 1/2CV² ... Equation 1

    Where Q = charge, V = potential difference, C = Capacitance of the capacitor.

    make V the subject of the equation

    V = √ (2W/C) ... Equation 2

    Given: W = 4 J,

    Substitute into equation 2 and find the value of V in terms of C

    V = √ (8/C)

    Since both capacitor were connected in parallel,

    The total potential difference = potential difference of on of the capacitor = √ (8/C)

    Total capacitance = 2C.

    using equation 1,

    W = 1/2 (√ (8/C)) ²*2C

    W = 8 J.

    Hence the right option is B. 8 J
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