Science — CBSE Class 10 board question

(a) When a bundle of soft iron wires is placed inside a current-carrying solenoid, the soft iron gets strongly magnetised. The device obtained is called an electromagnet. It is called so because it is a magnet created by electric current (it loses its magnetism when current is switched off).

(b)

(Diagram: parallel, straight, equally-spaced horizontal lines inside the solenoid, with arrows pointing in one direction)

The uniform parallel field lines inside the solenoid indicate that the magnetic field is uniform (equal in magnitude and same in direction) inside it, similar to a bar magnet.

Source: Chapter 12 – Magnetic Effects of Electric Current

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• For (a), two points are needed (2 marks): what happens (iron gets magnetised strongly) + name of device + reason for the name. "Electro" → electric current; "magnet" → behaves like a magnet.
• For (b), always draw the diagram (even a rough sketch scores marks) and state what uniform/parallel field lines mean — the examiner expects the word uniform magnetic field.
• Don't confuse electromagnet with a solenoid; the solenoid becomes an electromagnet when soft iron core is inserted.