Make it stronger

The idea

The strength of an electromagnet increases with the amount of current through the coil and with the number of turns of the coil, so it can be changed by changing either or both.

Pick up more clips

A coil joined to a single cell can attract only a few clips. You want it to pick up more.

What could you change to make the electromagnet stronger?

• Use more cells
• Switch the current off
• Paint the iron nail

Strengthen the magnet

Switch the current ON. Change the number of cells and the number of turns. Pick up 6 or more clips.

Current and turns

More cells give a larger current, which makes a stronger magnetic field. More turns of the coil also make a stronger magnet. You can change one or both.

The strength of an electromagnet can be changed by changing the amount of electric current through the coil, the number of turns of the coil, or both.

• What you change | Effect on the electromagnet
• More cells (larger current) | Stronger
• More turns of the coil | Stronger

Notes

The strength of an electromagnet can be changed by changing the amount of current, the number of turns of the coil, or both.

Check yourself

A battery of more cells gives, compared with one cell, …

Which coil is the stronger electromagnet?

You increase the number of turns of the coil. The electromagnet becomes …

What can you change to change the strength of an electromagnet?

• a smaller current. More cells give a larger current.
• no current. A battery of cells gives current.
• a larger current — correct. Yes!
• The coil joined to 3 cells — correct. Yes!
• The coil joined to 1 cell. A single cell gives only a small current, so the magnetic field is weak.
• Both are equally strong. The amount of current changes the strength.
• weaker. More turns make the coil a stronger magnet.
• stronger — correct. Yes!
• exactly the same. Increasing the turns changes the strength.
• Only the colour of the wire. Colour does not matter. The current and the number of turns do.
• Nothing, the strength never changes. The strength can be changed in these ways.
• The current or the number of turns, or both — correct. Yes!