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Question:

what would happen if I connected an electric motor rated for 220volts up to a regular 120volt house circuit?

I have a small 1/4 HP 220V AC motor, and I want to see if it will run on a regular household 120V AC circuit. Will it work?

Answer:

poorly. It will rotate slowly if at all, and may overheat. .
It won't work; it will not start. Insufficient torque being developed due to insufficient current. All that will happen is that the motor will get warm.
Motor torque is proportional to the square of applied voltage in per unit of rated voltage. So if you apply 120 v on a 220 volt motor, that's 0,54 per unit voltage, or about 0.3 per unit torque. It will get warm, it will struggle to accelerate, but probably won't be able to overcome friction to breakaway from standstill. Eventually, either the motor will fail thermally, or its thermal overload will disconnect the power.

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