Question 60
In this activity, you will carry out investigations and plan further investigations on the strength of electromagnets. Work in groups of two or three.
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 1 – changing the number of turns in the coil
1. Make an electromagnet. Use the number of cells or the power supply setting that your teacher advises. (You should recall how to make an electromagnet from Topic 9.3.) Use the iron nail for the core. Wrap the wire around the core to make five turns.
2. Switch on the electromagnet and see how many paperclips it will hold. Record this result.
3. Switch the electromagnet off and increase the number of turns on the coil by five.
4. Switch on the electromagnet and see how many paperclips it will hold. Record this result.
5. Repeat steps 3–4 until you can’t fit any more turns on the core.
6. Repeat the entire investigation. If any of your results are different, you may need to repeat them a third time.
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 1 – changing the number of turns in the coil
1. Make an electromagnet. Use the number of cells or the power supply setting that your teacher advises. (You should recall how to make an electromagnet from Topic 9.3.) Use the iron nail for the core. Wrap the wire around the core to make five turns.
2. Switch on the electromagnet and see how many paperclips it will hold. Record this result.
3. Switch the electromagnet off and increase the number of turns on the coil by five.
4. Switch on the electromagnet and see how many paperclips it will hold. Record this result.
5. Repeat steps 3–4 until you can’t fit any more turns on the core.
6. Repeat the entire investigation. If any of your results are different, you may need to repeat them a third time.
