The current in a wire is doubled. What happens to the field around it?
The same scrapyard crane now faces a heavier load: a packed van body. The operator does not swap the magnet. He turns the current up, and the magnet holds the van body.
Earlier in this topic you saw that more current makes a stronger magnetic field. So turning the current up makes the electromagnet attract its load more strongly. Turning the current down weakens the attraction.
A permanent magnet has no such setting: its strength is fixed.
On a bench, the same electromagnet at 2 A holds 4 steel sheets. At 6 A it holds 12 steel sheets.
A lifting electromagnet must hold a heavier plate. What should the operator do?
An electromagnet's pull is too strong for the job. What should the operator do?
A salvage magnet must lift a heavier steel beam than usual. What should its operator change?
More current makes a stronger electromagnet.
Turn the current up.
The same beam must be set down gently, a little at a time. How can the magnet's hold be eased off?
Less current makes a weaker electromagnet.
Lowering the current weakens the attraction a little at a time.
Turn the current down, step by step.
Iris says a driver can set an electromagnet's strength by setting its current. Is Iris correct?
A workshop hoist must lift light brackets gently and heavy plates firmly. Why does an electromagnet suit this job?
A lifting magnet's current is turned down a little, mid-lift. What happens to its pull on the load?
A job needs a magnet whose pull can be doubled during use. Why is a permanent magnet the wrong choice?