Capacitor Physics Problem?

ellie-davis_60c12dbfc3382ellie-davis_60c12dbfc3382
in Science & Mathematics

Capacitors C1 and C2 are charged respectively by 10V and 20V batteries. Each capacitor is then disconnected from its battery and attached to the other capacitor. If the voltage across the combination is found to be 14V and the total energy of the combination is 490uJ, determine C1 and C2.

I know how to solve problems with two capacitors in regards to charge and voltage but I am thrown off when they give me total energy of the combination. How would I approach this problem?

Comments

  • ivan-aivan-a

    The energy stored in a capacitor is given by

    E = 1/2 C V^2 =1/2 (C1 + C2) V^2

    And, from charge conservation, we have

    C1 V1 + C2 V2 = (C1 + C2) V

    now you have two equations and two unknowns, you can solve for C1 and C2.

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