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Thread: Help with this question please

  1. #1
    Cadet
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    Help with this question please

    I know that at maximum speed the back emf that a motor has is approximately equal to the supply emf, (which ultimately causes its speed to cap). But im confused with the words "it draws a current of 4A".

    Its probably not a complicated issue at all, just a little confused, any help would be nice

    https://imgur.com/5Y6BF69

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    Senior Member jazz519's Avatar
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    Re: Help with this question please

    Knowning that are 4 amps of current flowing through the wires, lets u find the total EMF in the coil

    since you have to use the equation EMFcoil = EMFsupply - EMFback = IR

    So EMFcoil = 4 x 2.0 = 8.0 volts

    thus 8.0 = 240-EMFback, so EMFback = 232 volts
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