NCERT Solutions Curiosity Chapter 4 Sections 4.1.2 and 4.2 — In-text Questions

Book page 52 Updated on2026-09-05

Q1.

Are electromagnets also used in real life, for lifting objects?

Answer

Yes — these are called lifting electromagnets. They are very strong electromagnets that may be hung from cranes in place of the usual hook.

Crane operator does this	What happens
Switches the current ON	The electromagnet becomes a magnet and lifts the iron or steel objects
Switches the current OFF	The magnetic field disappears and the objects are released

They are widely used in factories and scrap yards, to move, lift and sort heavy metal items efficiently.

Why an electromagnet and not a permanent magnet: a permanent magnet would hold the load and never let go. Because the electromagnet's magnetism exists only while the current flows, the operator can pick up a tonne of scrap at one place and drop it at another by doing nothing more than flicking a switch.

Q2.

While doing the activity for electromagnet, did you also notice that the wire ends got warm? Why would that happen?

Answer

Yes — and that warmth is the heating effect of electric current, the second effect this chapter is about.

Why it happens: when current flows through any conductor, it faces some opposition, called resistance. Because of this resistance, part of the electrical energy is converted into heat energy inside the wire, and the wire becomes warm. It happens in every current carrying wire — the coil of an electromagnet included. In the electromagnet activity the coil is connected straight across the cell, so a fairly large current flows and the warming becomes easy to feel at the ends.

Tip: this is also why the book tells you not to keep the coil connected to the cell for more than a few seconds. The energy going into heating the wire is energy taken from the cell, so the cell weakens quickly.

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