Question 65
You will need:
- three 1.5 V cells or an adjustable d.c. power supply with safety cut-out (d.c. means the current flows in the same way as from cells. A safety cut-out stops the current from becoming too large.)
- leads and connectors; switch; ammeter; iron nail
- paperclips of different sizes; plastic-coated wire at least 1 m long with about 1 cm of plastic removed from each end; selection of similar-sized cores to the iron nail, such as a wooden pencil, roll of paper, plastic pen and at least one other metal.
Safety: Only keep your electromagnet switched on for the shortest possible time, otherwise your cells will not last long. Check that the wire in the coil is not becoming hot. If the wire becomes hot, switch off immediately and tell your teacher.
Method: Part 2 – changing material in the core
1. Make an electromagnet. Use the iron nail as the core. Wrap the maximum number of turns in the coil that will fit on the core. Use the number of cells or the power supply setting that your teacher advises.
2. Switch on the electromagnet and see how many paperclips it will hold.
3. Repeat this with other core materials. The other cores should be about the same diameter, so you should not have to unwind the coil each time.
4. As in Method: Part 1, repeat each of your measurements.
- three 1.5 V cells or an adjustable d.c. power supply with safety cut-out (d.c. means the current flows in the same way as from cells. A safety cut-out stops the current from becoming too large.)
- leads and connectors; switch; ammeter; iron nail
- paperclips of different sizes; plastic-coated wire at least 1 m long with about 1 cm of plastic removed from each end; selection of similar-sized cores to the iron nail, such as a wooden pencil, roll of paper, plastic pen and at least one other metal.
Safety: Only keep your electromagnet switched on for the shortest possible time, otherwise your cells will not last long. Check that the wire in the coil is not becoming hot. If the wire becomes hot, switch off immediately and tell your teacher.
Method: Part 2 – changing material in the core
1. Make an electromagnet. Use the iron nail as the core. Wrap the maximum number of turns in the coil that will fit on the core. Use the number of cells or the power supply setting that your teacher advises.
2. Switch on the electromagnet and see how many paperclips it will hold.
3. Repeat this with other core materials. The other cores should be about the same diameter, so you should not have to unwind the coil each time.
4. As in Method: Part 1, repeat each of your measurements.
