Solenoid Chute

It’s electrifying! Get things moving with your very own electromagnet!

Australian Curriculum links

  • Science > Physical Sciences > Year 4 > ACSSU076

You'll need

  • plastic straw
  • 1 metre coated copper wire (eg. winding wire)
  • scissors
  • good quality 1.5 V (AA) battery
  • paper clip

Try this

  1. Hold the wire about 15 cm from one end and start wrapping the wire around the straw, working from one end of the straw to the other. Wind the wire so the gap between each coil is smaller than 1 mm. Stop winding when you have about 15 cm of wire remaining at the other end.
  2. Lay the straw on a flat surface. At each end of the wire, use scissors to scratch off some of the coating to expose the copper wire.
  3. Unfold the paper clip and straighten it.
  4. Place the unfolded paper clip in one end of the straw so half of the paper clip is inside the solenoid (wire coil).
  5. Hold one end of the wire against the positive terminal of the battery.
  6. Touch the other end of the wire to the negative terminal of the battery and watch the paper clip move!

Note: Don’t leave the wire connected to the battery for too long as the wire will become hot.

What's happening?

When both ends of the wire are connected to the battery, an electrical current flows in the coiled wire. This electrical current creates a magnetic field inside the straw. The paper clip is attracted to the magnetic field in the straw and this force of attraction pulls the paper clip into the straw.

A ‘solenoid’ is another name for a coil of wire. Solenoids are very useful because of the fact that an electrical current in a solenoid creates a magnetic field inside the coil of wire. A magnet created in this way is called an ‘electromagnet’. The magnetic field of an electromagnet behaves in much the same way as the magnetic field that surrounds a permanent magnet (eg. a bar magnet or a fridge magnet). However, an electromagnet has the advantage that it can be switched on and off by switching the electrical current on or off. The magnetic field inside a solenoid is very uniform if the wire of the solenoid is coiled around a metal core so most electromagnets consist of wire wound around a metal core.

Real world links

Electromagnets are used in a lot of electrical devices in which the movement of a metal object is controlled by turning an electrical current on or off. For example, in older doorbells, when the button is pushed, electrical current flows in an electromagnet, which causes a small hammer to bang against the bell. In car wrecking yards, very large electromagnets are used to pick up and move old cars.