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NCERT Solutions Curiosity Chapter 4 Activity 4.7: Let us investigate — — Does the magnetic effect pass through other materials?

Book page 70 & 71 Updated on2026-09-05

Q1.
Suppose we place a piece of wood between the compass needle and the magnet. Will this affect the deflection of the compass needle?
Answer

No, it will not. The compass needle deflects by very nearly the same amount as before. The wood does not block the magnetic effect.

Magnet → air → needle : needle deflects
Magnet → wood → needle : needle still deflects, by about the same amount
Why it happens: wood is a non-magnetic material. The magnetic effect of a magnet passes straight through non-magnetic materials as if they were not there. Only the distance between the magnet and the needle really matters — so keep the magnet at the same distance while sliding the wood in, or you will fool yourself.
Q2.
Is there any effect on the deflection of compass needle due to the piece of wood? Record your observation in Table 4.2.
Answer

There is no appreciable effect. Record it like this:

S. No.Material placed between the magnet and the compass needleObservation
1.WoodThe needle deflects as before — no appreciable change in the deflection
Check it yourself: Do it in the right order — first note the deflection with nothing in between, then slip the wood in without moving either the magnet or the compass, and note the deflection again. Comparing the two readings is what makes the result trustworthy.
Q3.
Repeat the process by replacing the piece of wood with a cardboard sheet, thin plastic sheet, and a thin glass sheet.
Answer

The result is the same for all four. Completed Table 4.2:

S. No.Material placed between the magnet and the compass needleObservation
1.WoodNo appreciable change in the deflection
2.CardboardNo appreciable change in the deflection
3.PlasticNo appreciable change in the deflection
4.GlassNo appreciable change in the deflection

Conclusion:

The magnetic effect can act through non-magnetic materials — wood, cardboard, plastic and glass do not stop it.
Where you meet this every day: a fridge magnet holds a thick sheet of paper against the steel door — the magnetism reaches through the paper. In the maze game of Fig. 4.12, a magnet moved below a cardboard tray drags the steel balls above it. A shop's glass door magnet, and the magnet inside a pencil-box flap covered with cloth, work the same way.
Did you know? A sheet of soft iron does weaken the effect a lot, because iron is magnetic and takes the magnetism into itself. That is why the chapter tells you to store magnets with two pieces of soft iron across their ends.
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