Req 3 — Build an Electromagnet
A permanent magnet always acts like a magnet. An electromagnet only becomes magnetic when electric current flows through it. That makes electromagnets one of the coolest examples in this badge, because they show electricity doing real physical work.
The basic idea is simple: when current moves through a wire, it creates a magnetic field. If you wrap the wire into coils, those magnetic effects add together. If you wrap the coil around an iron nail or bolt, the iron helps concentrate the field and makes the magnet stronger.
What You Need to Understand
A simple electromagnet usually has four parts:
- Battery: pushes current through the circuit.
- Wire: carries the current.
- Coil: strengthens the magnetic field by looping the wire.
- Iron core: focuses and boosts the magnetic effect.
When the circuit is open, nothing happens. When the circuit is closed, the current flows and the nail or bolt can pick up steel objects like paper clips.
A Simple Build Plan
Your counselor may want you to build this live or explain the process clearly. A common setup uses insulated wire wrapped around an iron nail and connected to a battery.
Electromagnet build steps
Keep it simple and safe
- Wrap insulated wire around an iron nail, leaving free wire at both ends.
- Strip the insulation from the two ends if needed so the battery can make contact.
- Connect the ends to a battery briefly.
- Test the magnet by picking up paper clips or small steel washers.
- Disconnect the battery when not actively testing so the wire does not overheat.
Showing Attraction and Repulsion
Attraction is the easier part to demonstrate. Your electromagnet should attract iron or steel items when current is flowing.
Repulsion takes a second magnet. If you bring your electromagnet near a permanent magnet or another electromagnet, sometimes the poles will attract and sometimes they will push apart. That depends on which magnetic poles are facing each other. Like poles repel. Opposite poles attract.
One neat experiment is to reverse the battery connections. When you reverse the current direction through the coil, the magnetic poles reverse too. That can change an attraction setup into a repulsion setup.
Why This Matters
Electromagnets are everywhere. Doorbells, relays, motors, speakers, maglev trains, MRI machines, and industrial lifting equipment all rely on the link between electricity and magnetism. This requirement is not just a craft project. It is your first look at a principle that powers real machines.
Khan Academy — Electromagnetism A clear explanation of how electric current creates magnetic fields and how coils make electromagnets stronger.