NCERT Solutions Curiosity Chapter 1 Batteries, lamps and wires; the changes around us — In-text Questions
Book page 3 Updated on2026-09-05
Q1.
What kind of materials do we need to make a lamp glow?
Answer
We need materials that let electricity pass through them. These are called conductors — and almost all of them are metals.
Look at the photograph on page 3 of your book: a cell, two wires, a small bulb in a holder — and a steel spoon joined into the loop. The bulb glows because the spoon is metal, so the circuit is complete all the way round.
The simple tester you will build: cell, wires, bulb and a gap. Put the object in the gap and watch the bulb.
Bulb glows — conductors
Bulb does not glow — insulators
Copper wire, iron nail, steel spoon, aluminium foil, coin
Why it happens: the bulb needs a complete, unbroken path for the current. If the object in the gap is a conductor, the path is closed and the bulb lights; if it is an insulator, the path stays broken and nothing happens. Notice what this simple test really gives you — a way to sort materials by a property. Sort enough of them and two clear families appear: metals and non-metals.
Tip: If the bulb refuses to glow even with a spoon, check the boring things first — a loose wire end, a dead cell, or a painted spoon handle. Good scientists rule out the simple causes before inventing clever ones.
Q2.
Batteries run out, ice melts into water, fruits ripen, rocks break into pebbles… what kind of changes are these?
Answer
They are all changes, but they fall into two families: some can be reversed and some cannot.
Change
Can it be reversed?
Why
Ice melts into water
Reversible
Cool the water and you get ice back — it is the same substance, only its state has changed
A torch battery runs out
Irreversible
The chemicals inside have changed into new substances; no amount of shaking brings them back
A fruit ripens
Irreversible
Starch has turned to sugar and the acids are used up; a ripe mango never becomes raw again
Rocks break into pebbles
Irreversible
The material is still rock, but the broken pieces cannot be joined back into the original rock
Two more things the chapter wants you to notice:
Heat changes the speed. Many of these happen only on heating, or happen much faster when heated — mangoes ripen faster in May than in December, and ice melts faster in a warm room.
Fast and slow. Ice melting takes minutes; a rock crumbling into pebbles takes thousands of years. Both are changes.
Why it happens: in a reversible change only the form or state of the material changes, and the original material is still there. In an irreversible change new substances are formed, or the pieces can no longer be put back, so there is no way home.
Check it yourself: Curd from milk, a burnt matchstick and a rusted nail — reversible or irreversible? All three are irreversible. Now try: wet clothes drying, and a rubber band stretched. Both reversible.