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9.1Physics 03. Electricity And Magnetism

Electricity as a flow of electrons conductors and insulators — Cambridge Checkpoint Science 0893 Revision Notes & Topical Questions

5 min read 9 parts Lesson 1 of 5 1 quiz

📚 Cambridge Checkpoint Science 0893 Hub / Topical Revision
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Lesson summary

9.1 Electric current as a flow of electrons: conductors and insulators — CHECKPOINT - Lower Secondary Science 0893 notes: Describe electric current as a flow of electrons around a complete circuit and distinguish conductors from insulators.Cell — stores chemical energy that is ch…

  • Faster flow
  • Free electrons
  • In a circuit
  • Loop of string
  • Battery — two or more cells joined together
  • Terminals — every cell, battery and power supply has a positive (+) and a negative (-) terminal

Part 1 of 7Cells and batteries

Cell
  • Cell stores chemical energy that is changed to electrical energy in a circuit.
Battery
  • Battery two or more cells joined together.
Terminals
  • Terminals every cell, battery and power supply has a positive (+) and a negative (-) terminal.

Part 2 of 7Electric current

1Current
  • Current the flow of electrons around a circuit.
  • Electrons are small particles in atoms that carry a negative charge.
2Complete circuit
  • Complete circuit electrons flow only when the circuit is complete, so a break stops all the flow.
3Faster flow
  • Faster flow a faster flow of electrons is a greater current.

Part 3 of 7Electrons in a metal

Free electrons
  • Free electrons in a metal some electrons are free to move through the metal.
  • Without a circuit they move randomly.
In a circuit
  • In a circuit the free electrons all move in the same direction around the circuit.

Part 4 of 7Direction of the flow

1Charges
  • Charges opposite charges attract and like charges repel.
2Movement
  • Movement the electrons are repelled by the negative terminal and attracted towards the positive terminal.
  • So electrons flow from the negative terminal to the positive terminal through the wires.

Part 5 of 7Conductors and insulators

Material typeBehaviourExamples
Electrical conductorAllows current to flow because it has free electronsMetals such as copper
Electrical insulatorDoes not allow current to flowPlastic, rubber, glass, wood
  • Uses
    • copper wire carries current and plastic around the wire stops the current flowing out.

Part 6 of 7Testing a material

1
Make a simple circuit with a cell and a lamp.
2
Connect the material into a gap in the circuit.
3
If the lamp lights, the material is a conductor.
4
If the lamp does not light, the material is an insulator.

Part 7 of 7Model of current

  • Loop of string
    • the cell pulls the string and all the string moves at once.
    • Current starts everywhere in the circuit at the same time, all the way round.

Key terms

TermMeaning
CurrentFlow of electrons in a circuit.
ElectronNegatively charged particle in an atom.
CellA source of electrical energy from chemical energy.
TerminalA connection point of a cell, marked + or -.
ConductorMaterial that lets current flow.
InsulatorMaterial that does not let current flow.

Avoid these mistakes

1
Current is used up by the lamp — electrons keep flowing around the whole circuit.
2
Electrons flow from positive to negative — they flow from the negative terminal to the positive terminal.
3
Electrons start at the cell and take time to reach the lamp — the free electrons are in the wire and move at once.
4
A circuit works with a gap in it — electrons flow only in a complete circuit.

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