|When a current passes through the solenoid in picture 6, it becomes an electromagnet. So one end is a north pole and the other end is a south pole. There is a little trick for remembering which end becomes which pole. |
It's a question of seeing whether the letter S or N will point in the same direction as the current.
When we look at one end of the coil, the current is going anticlockwise. In this case, we can put in the letter N and it will point in the same direction as the current. An S will not. So this is the north pole.
If we look at the other end of the coil, the current is going clockwise. In this case we can fit in an S. So this is the south pole.