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    Micro-F Capacitor

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    Hi. Can someone please check these two answers? (a) seems very low and (b) seems very high to me.

    A 0.22 micro-F capacitor is charged by a 1.5-V battery. After being charged, the capacitor is connected to a small electric motor. Assuming 100% efficiency, (a) to what height can the motor lift a 5.0-g mass? (b) What initial voltage must the capacitor have if it is to lift a 5.0-g mass through a height of 1.0 cm?

    My solutions:

    (a)
    C = 0.22 micro-F = 0.22 x 10^-6 F
    V = 1.5 V
    m = 5.0 g = 5.0 x 10^-3 kg
    h = ?

    Q = CV = 3.3 x 10^-7

    U = (1/2)QV = 2.5 x 10^-7 J

    ANSWER: U = mgy , y = U/mg = 5.1 x 10^-6 m

    (b)
    V = ?
    m = 5.0 x 10^-3 kg
    C = 0.22 x 10^-6
    h = 1 cm = 0.01 m

    U = mgy = 4.9 x 10^-4 J

    ANSWER: U = (1/2)QV , V = U /(1/2)Q = 2970 V

    Thank you.

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    https://brainmass.com/physics/work/micro-capacitor-voltages-23618

    Solution Preview

    Your work for (a) is certainly correct.

    Your work for (b) is certainly correct.

    Whoever wrote the question certainly didn't use realistic examples. Although (a) is a bit realistic if you think of MEMS (Micro-electro-mechanical systems). Moving a micro-mechanical beam 5.1um ...

    Solution Summary

    The expert examines micro-F capacitor voltages. The solution includes a 150-200 word explanation.

    $2.19

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