NCERT Solutions Curiosity Chapter 4 Activity 4.4: Let us design and create — Conduction of electricity
Book page 47 & 48 Updated on2026-09-05
Q1.
Design an electric circuit, like the ‘tester’ circuit in the chapter ‘Electricity: Circuits and their Components’. Repeat the same activity using the materials listed below and record your observations in Table 4.2.
Answer
Build the tester first, then use it to test each object.
Join a cell, a bulb in a holder and connecting wires so that the circuit has a gap with two free ends.
Touch the two free ends together once — the bulb must glow. That check tells you the tester itself is working.
Now hold the object to be tested across the gap, so that it completes the circuit.
If the bulb glows, electricity has passed through the object.
The tester: the object being tested is placed in the gap. A glowing bulb means electricity passed through it.
Tip: scrape the surface of an old nail or a coal piece clean before testing. A dirty or coated surface can stop contact and give you a wrong “does not glow”.
Q2.
Predict which of these could make the bulb of the tester glow and which could not. (Objects: a piece of aluminium foil, an iron nail, a lump of sulfur (pea-sized), a copper wire, a piece of coal, a piece of dry wood, a stone, an eraser made of rubber and a piece of nylon rope.)
Answer
Write the prediction first, then test. A completed Table 4.2 looks like this.
S.No.
Object/Material
Observation (bulb glows/does not glow)
Good or poor conductor of electricity
1.
Piece of aluminium foil
Glows
Good conductor
2.
Iron nail
Glows
Good conductor
3.
Lump of sulfur (pea-sized)
Does not glow
Poor conductor
4.
Copper wire
Glows
Good conductor
5.
Piece of coal
Does not glow
Poor conductor
6.
Piece of dry wood
Does not glow
Poor conductor
7.
Stone
Does not glow
Poor conductor
8.
Eraser made of rubber
Does not glow
Poor conductor
9.
Piece of nylon rope
Does not glow
Poor conductor
Q3.
Do you see any pattern in the glowing of bulbs when using different materials in Activity 4.4?
Answer
Yes — a very clear pattern. Every material that made the bulb glow is a metal.
Aluminium, iron, copper → bulb glows → metals
Sulfur, coal, wood, stone, rubber, nylon → bulb does not glow → non-metals and other materials
Materials that allow electricity to flow through them easily are called good conductors of electricity. Materials that prevent the bulb from glowing by not allowing electricity to pass through them are called poor conductors of electricity.
Why it matters: this single pattern explains the electrician's kit. The wires are metal so that current flows, and the screwdriver grip, gloves and shoes are plastic and rubber so that current cannot flow into the body.