A permanent electromagnet can be obtained from a current-carrying solenoid if the solenoid is wound around a ferromagnetic core (like iron) and the current is maintained for a sufficient duration to magnetize the core. The core should be a material with high retentivity, meaning it can retain its magnetism even after the current is removed.
Labelled Circuit Diagram:
+—.
| | Battery
+—+–.
| |
+–+ |
| | |
| | |
| | |
+–+ |
| |
+—+ |
| | |
| | +—.
| | | |
| | | |
+—+ | | Solenoid Coil
| |
| +—.
| | |
| | |
| | |
| +—+
|
+—.
| |
+—+
+—.
| | Iron Core
+—+
Explanation of the Diagram:
Battery: Provides the direct current needed to energize the solenoid.
Solenoid Coil: A coil of wire that, when carrying current, creates a magnetic field.
Iron Core: A ferromagnetic material (like steel or iron) placed inside the solenoid. The magnetic field from the solenoid magnetizes the iron core, making it act as a permanent magnet after the current is removed.