Electromagnet Strength
Aim: To investigate how current, coil turns and core material affect the strength of an electromagnet.
Close the switch, then count the paperclips it can hold. Change one variable at a time and record your results. Use the Graph Builder to plot them.
Paperclips held
0
Ammeter
0.0 A
The steel core has kept some of its magnetism — it has become a weak permanent magnet. An iron core loses its magnetism as soon as the current stops.
Power
Core material
Results
| # | Core | Turns | Current (A) | Paperclips |
|---|
- Choose the iron core, set the current to 1.0 A with 10 turns, and switch on. Record the number of paperclips.
- Keeping the turns and core the same, increase the current in 0.5 A steps, recording the paperclip count each time.
- Now keep the current fixed and change the number of turns. Record at least 5 readings.
- Finally, compare the air, iron and steel cores with the same current and turns.
- Plot a graph of paperclips against current. What pattern do you see? What happens when you double the current?
- Switch off while using the steel core, then while using the iron core. What is different, and why does this make iron a better choice for an electromagnet?