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Electricity: Circuits and their Components

Track quiz

Here are the rules this track used. Read them, then try the questions.

Circuits — what decides whether the lamp lights
IdeaThe rule
The loopThe lamp glows only when the path is closed, with no gap.
SwitchA switch opens or closes the gap. ON is closed. OFF is open.
ConductorsA conductor lets electric current through. An insulator does not.
SymbolsEvery part has a symbol. A drawing made of symbols is a circuit diagram.
BatteryJoin the + of one cell to the − of the next. Turn one of two cells round, and their pushes cancel. The lamp stays dark.
One loopParts in one loop share one path. Take one out and every lamp goes dark.
SafetyUse only cells for experiments. Keep your hands dry. Never use a damaged wire.
LEDAn LED lets current through one way only. It glows only when its long leg meets the + end.
Two kinds of currentA cell gives direct current, which flows one way. A wall socket gives alternating current, which keeps reversing.
Dark lampA dark lamp has a reason. Check the switch, the lamp, the cell and the wire ends.

A lamp is joined to a cell by one wire only. What happens?

  • It glows, but only half as brightly
  • Nothing. There is no path back to the cell
  • It glows once, then goes out

The cell is taken out. The switch on the loop is closed. What does the lamp do?

  • It lights, because the switch is closed
  • It flickers
  • Nothing. A switch does not push anything

A rubber eraser is put in the gap of a closed loop. What happens?

  • The lamp stays dark. Rubber is an insulator
  • The lamp lights. Rubber is a conductor
  • The lamp lights dimly

You see two dots with a line lifted off one of them. What is it?

  • A cell, drawn as two lines
  • A switch that is OFF
  • A lamp

Two cells sit in a torch. One is put in the wrong way round. What happens?

  • The lamp lights more brightly
  • Nothing changes
  • The lamp stays dark

Two lamps sit on one loop. One lamp is taken out. What happens to the other?

  • It goes dark
  • It glows brighter
  • It stays lit

Which plan is safe for an experiment?

  • A wall socket
  • Wet hands on a switch
  • A torch cell and a lamp, with an adult beside you

An LED stays dark in a closed loop with a good battery. What might be wrong?

  • Its filament wire has burnt through
  • It is joined the wrong way round
  • The wires are too long

Which of these gives direct current?

  • A torch cell
  • The wall socket in a kitchen
  • The mains supply in a house

The lamp is dark. The switch is closed and the cell is good. What else could be at fault?

  • A wire end covered with plastic
  • The lamp is too bright for the cell
  • The loop is too short for the cell

Now open Chapter 3 in your NCERT book. You have built every circuit in it here.

The next track is The World of Metals and Non-metals. You have already met a pencil lead that conducts.

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This track

  1. 0 Start here
  2. 1 The loop has to be unbroken
  3. 2 A switch is a gap you can close
  4. 3 Some things let the loop through
  5. 4 A drawing everyone reads the same way
  6. 5 Two or more cells make a battery
  7. 6 One loop, one break, everything stops
  8. 7 Cells are for experiments
  9. 8 Checkpoint: loops, switches, parts and safety
  10. 9 An LED has a right way round
  11. 10 Two kinds of electricity
  12. 11 Why a lamp may stay dark
  13. 12 Checkpoint: LEDs, kinds of current and faults
  14. 13 The big picture
  15. 14 Track quiz

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