Method:

1) Punch paper fasteners through the card about 2 cm apart.

2) Tape a wire to the plus end of the battery and another to the minus end.

3) Attach the wire taped to the - end of the battery to the bottom of the bulb.

4) Connect the wire taped to the + end of the battery to one of the paper fasteners.

5) Use the third wire to join the second paper fastener to the side of the bulb.

Result: When you turn the paper clip, so that it touches both paper fasteners, the circuit is made and the bulb lights. Move the paper clip away from one of the paper fasteners and the circuit is broken and the bulb goes out. The diagram above did not use a paper clip - instead the paper fasteners were turned to touch each other at the bottom of the card.

Conclusion: If the paper fasteners do not touch each other, then the electricity does not flow round in a circle and the circuit is broken. If they touch, the circuit is complete and the light goes on.

Our Experiments