Checkpoint: what current does

Two wires have the same length and carry the same current. One is thin and one is thick. Which warms more?

• The thick wire
• Both warm the same
• The thin wire

Which part of a circuit melts when the current is too large?

• The cell
• The fuse
• The switch

A compass needle near a wire swings when the switch is closed. What does this show?

• The wire has turned into iron
• The compass is broken
• There is a magnetic field around the wire

Which change makes a coil with an iron core pull more clips?

• Taking out one cell
• Adding more turns of wire
• Pulling out the iron core

The switch of an electromagnet is opened. What happens to the pins it held?

• They are held for a minute
• They fall
• They stay held