← Back to the activity

Year 7 Science — Circuits and their components

Name the parts of a torch circuit and what each does, read a circuit diagram's symbols, tell a conductor from an insulator, and say when a lamp glows and when it does not.

Name: ________________________

Before you start

Take apart an incandescent torch lamp and look at what makes the light.

1234
  1. 1. Glass bulb
  2. 2. Filament
  3. 3. Metal case
  4. 4. Metal tip

The filament is the thin wire that gets hot and glows. The metal case and the metal tip are the lamp's two terminals, kept apart so they cannot touch. An LED lamp has no filament inside it — it makes light a different way.

  1. 1.In the symbol for an electric cell, one line is drawn long and one short. What does the long line stand for?

    • a) The amount of energy left in the cell
    • b) The positive terminal
    • c) The wire leaving the cell
    • d) The negative terminal

  2. 2.Silver, copper and gold are the three best conductors. Why is the metal inside an electric wire usually copper?

    • a) Copper is easier to draw into a thin wire than any other metal
    • b) Silver and gold are insulators
    • c) Copper costs less and there is plenty of it, and it conducts nearly as well
    • d) Copper is the one metal that conducts electricity

  3. 3.Match each part of a torch circuit to the job it does.

    • Electric cell
    • Switch
    • Filament
    • completes or breaks the circuit
    • a portable source of electrical energy
    • gets hot and glows to give light

  4. 4.This is the circuit diagram of a torch. Tap the symbol for the switch.

    Write the number of the part.

    123

  5. 5.A drawing that stands in for a real circuit, made out of the agreed symbols rather than pictures, has a two-word name. What is it?

  6. 6.Two or more electric cells joined cap-to-disc, so the positive terminal of one meets the negative terminal of the next, are together called what?

  7. 7.An LED is joined to a battery and does not light. What is the first thing worth checking?

    • a) Whether the battery has too many cells in it
    • b) Whether its filament has broken
    • c) Whether its longer wire is on the battery's positive terminal
    • d) Whether it has been fitted the right way up in its holder

  8. 8.Each of these was held across the two free ends of a tester's wires. Sort them by whether the lamp glowed.

    Groups: Conductor · Insulator

    • Copper wire
    • Plastic scale
    • Metal key
    • Wooden stick
    • Rubber eraser
    • Aluminium foil

Answer key — Year 7 Science — Circuits and their components

  1. 1. b) The positive terminal
  2. 2. c) Copper costs less and there is plenty of it, and it conducts nearly as well
  3. 3. Electric cell → a portable source of electrical energy; Switch → completes or breaks the circuit; Filament → gets hot and glows to give light
  4. 4. 3 — Switch
  5. 5.
    • circuit diagram
    • a circuit diagram
    • the circuit diagram
  6. 6.
    • battery
    • a battery
  7. 7. c) Whether its longer wire is on the battery's positive terminal
  8. 8. Copper wire → Conductor; Metal key → Conductor; Aluminium foil → Conductor; Plastic scale → Insulator; Rubber eraser → Insulator; Wooden stick → Insulator