Question

how can we determine the pole of the electro magnet

Answer 1

The end of the compass needle which usually points north will be repelled by the north pole of your electromagnet and attracted by the south pole. You can check this against a permanent magnet with labeled north and south poles by bringing the same compass close to it.

Answer 2

The polarity of the electromagnet isdetermined by the direction the current. The north pole of the electromagnet is determined by using your right hand. Wrap your fingers around the coil in the same direction as the current is flowing (conventional current flows from + to -).

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