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Help with this question please (1 Viewer)

shehan123

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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
 

jazz519

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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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