- Draw a battery with the positive terminal (+) and negative terminal (-) labeled. Connect a wire coil around an iron core (like a nail). Show magnetic field lines emerging from one end of the coil (North pole) and entering the other end (South pole), using arrows to indicate direction. The North pole is at the end where current flows counterclockwise when viewed from that end (right-hand rule).
- When you hold a nail or paper clip near the energized coil, it will be attracted to the coil and may stick to it because the coil becomes magnetized when current flows through it.
- Reverse the battery connections so the positive terminal is now connected to the opposite end of the coil. Redraw the battery with reversed polarity. The magnetic field direction reverses: the former North pole becomes South, and vice versa. Magnetic field lines now emerge from the opposite end of the coil.
- After reversing the connection, holding a nail or paper clip near the coil still results in attraction — the electromagnet still works, but its magnetic poles are flipped.
- To test the strength, count how many paper clips the electromagnet can pick up at once. You can also test how far away the clip can be and still be attracted, or compare different coils (more turns, higher current) to see which picks up more clips.
- No, the electromagnet cannot pick up paper clips when the current is disconnected because the magnetic field disappears without electric current flowing through the coil.
Parent Tip: Review the logic above to help your child master the concept of electromagnet worksheet.
