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Class 7 Science: Electricity: Circuits and their Components, 8 practice questions with answers

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These are 8 practice questions on the third chapter of the new NCERT Class 7 Science textbook, Curiosity, called Electricity: Circuits and their Components. Each has a short answer and the textbook page it comes from. They cover cells and batteries, incandescent lamps and LEDs, a doorbell switch, circuit symbols, conductors and insulators, why a plug is part metal and part plastic, where electricity comes from, and a battery of three cells. For magnets, which the Class 6 book covers, see our Class 6 Exploring Magnets guide. Try each question before you read the answer.

These questions are our own, drafted with AI help. Every fact was checked against the page it cites by a test script, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity, Grade 7, Chapter 3, printed pages 23 to 40):

Cells and lamps

Question 1. (a) Why do many devices use more than one cell? (b) When cells are joined into a battery, how must their terminals meet? (c) The chapter calls a cell a portable source of electrical energy. What does "portable" mean here, and why does that suit a torch?

Answer: (a) for more energy and/or energy for a longer time; (b) the positive terminal of one cell touches the negative terminal of the next; (c) it can be carried about, so a torch works away from any wall socket. (a) Joining more than one cell gives the circuit more energy, or energy for a longer time, or both. (b) In a battery, each cell's positive terminal touches the next cell's negative terminal. (c) A portable source is one you can carry with you. A torch needs light wherever you take it, in a field or during a power cut, so it carries its own cells instead of being plugged in. (Cells and batteries, pages 25 and 26; electricity reaching homes through wires, page 24.)

Question 2. A torch's old incandescent lamp is replaced by an LED. (a) Which of the two has a filament? (b) Which works whichever way round it is connected, and which only one way? (c) How can you tell the positive leg of an LED?

Answer: (a) the incandescent lamp; (b) the incandescent lamp works either way, the LED only one way; (c) it is the longer wire. (a) In an incandescent lamp a thin wire, the filament, gets hot and glows. An LED has no filament. (b) An incandescent lamp glows whichever of its terminals is joined to the positive side of the cell. Current passes through an LED in one direction only, so it glows only when its positive terminal goes to the battery's positive terminal. (c) The LED's positive terminal has the longer wire. (Lamps and LEDs, pages 26, 27, 30 and 31.)

Circuits

Question 3. A battery doorbell rings only while its push button is held down. The button is a kind of switch. (a) While the button is pressed, is the circuit open or closed? (b) What happens in the circuit when the button is let go, and why does the ringing stop? (c) While the bell rings, in which direction is the current taken to flow?

Answer: (a) closed; (b) a gap opens, so no current flows; (c) from the positive terminal of the battery, round the circuit, to the negative terminal. (a) Pressing the button joins its two metal parts, which completes the path, so the circuit is closed and current flows through the bell. (b) When the button is let go, its parts spring apart and leave a gap; the circuit is open, no current flows, and the bell stops. A switch simply completes or breaks a circuit. (How a push button is built is our description; the chapter's rule is the open and closed circuit.) (c) In a closed circuit, the direction of the current is taken to be from the positive terminal of the cell or battery to the negative terminal. (Switches, page 32; direction of current, page 30.)

Question 4. In a circuit diagram: (a) in the symbol for a cell, which line stands for the positive terminal? (b) In the symbol for an LED, what does the triangle show, and what do the two small arrows show?

Answer: (a) the long line; (b) the triangle points the way current can flow, the arrows show that it gives out light. (a) In the cell symbol, the long line is the positive terminal and the short line the negative. (b) In the LED symbol, the triangle points in the direction the current can flow, and the two arrows show that an LED gives out light. (Circuit diagrams, pages 33 and 34.)

Conductors, insulators and where electricity comes from

Question 5. Using the chapter's rule about which kinds of material conduct electricity, sort these into conductors and insulators: an iron nail, a copper wire, a plastic comb, a ceramic tile, a rubber slipper.

Answer: conductors: the iron nail and the copper wire; insulators: the plastic comb, the ceramic tile and the rubber slipper. Materials through which current flows easily are conductors, and the chapter finds that metals, such as iron and copper, are conductors. Materials through which current cannot pass are insulators; the chapter names plastic, rubber and ceramics as insulators. (Conductors and insulators, pages 35 and 36.)

Question 6. The plug of a table lamp has metal pins and a hard plastic body. (a) Which part is a conductor and which an insulator? (b) Why must the pins be made of metal? (c) Why is the body made of plastic and not metal?

Answer: (a) the pins conduct, the body insulates; (b) so that current can pass through them into the lamp; (c) so that the person holding the plug does not get a shock. (a) Metal is a conductor and plastic is an insulator. (b) The pins must carry the current from the socket into the lamp's wire, and current flows easily only through a conductor such as a metal. (c) The body is the part we hold. An insulating body keeps the current inside the metal parts, away from our hand; the chapter says plug tops, switches and the covering of wires are made of insulators for exactly this reason. (Conductors and insulators, page 36.)

Question 7. (a) Name four ways of generating electricity that the chapter recalls from the Grade 6 book. (b) How does electricity from these sources reach our homes and factories?

Answer: (a) wind (windmills), sunlight (solar panels), falling water, and burning natural gas or coal; (b) through wires. (a) Electricity can be generated by windmills using the wind's energy, by solar panels that take in sunlight, by the force of falling water, and from natural gas or coal. (b) The supply from these sources is carried to our homes and factories along wires, which is why we can plug devices into the sockets in the wall. (Sources of electricity, page 24.)

Question 8. A toy needs a battery of three cells placed end to end in a row. (a) How many places are there where one cell touches the next, and which terminals meet at each? (b) Which two terminals are left free at the ends, to be joined to the rest of the circuit?

Answer: (a) two places, each a positive terminal against a negative terminal; (b) the positive terminal of the cell at one end and the negative terminal of the cell at the other end. (a) Three cells in a row touch in 2 places (between cells 1 and 2, and between cells 2 and 3). At each place the positive terminal of one cell meets the negative terminal of the next, as the chapter shows for two and four cells. (b) That leaves one positive terminal free at one end and one negative terminal free at the other, and these two are the battery's terminals. (Battery, pages 25 and 26.)

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Sources

All opened and read on 2 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 22 for this chapter.

The facts are from the textbook pages above. The questions, answers and checks are our own. This guide is general information; follow your teacher and the textbook.

Practise with the worksheet: Electric Circuits and Components, Class 7. Printable, in English, Hindi and Marathi, with an answer key.