Circuit Diagrams (AQA GCSE Physics): Revision Notes

2.1.1 Circuit Diagrams

Circuit Symbols:

Potential Difference (P.D.) in Series Circuits

Series Circuits

• Voltmeters:
• Always connected in parallel.
• P.D. Distribution:
• P.D. is shared in a series circuit.
• Total P.D. across components is the same as the P.D. across the cell.

Potential Difference in Parallel Circuits

Parallel Circuits

• P.D. Distribution:
  • For components connected in parallel, the potential difference across each component is the same.

Potential Difference from Batteries

Batteries

• Battery Definition:
• A battery is two or more cells connected together.
• P.D. Addition:
• The P.D. of cells adds up to give us the total P.D. of the battery.

Charge in Circuits

• Electrical Charge: Measured in coulombs (C).
• Current:
  • A current of 1 ampere = 1 coulomb of charge flowing per second.
  • The size of the electric current is the rate of flow of electrical charge.

Energy Transfer by Components

Resistance

Relationship Between P.D., Current, and Resistance

Current in Series Circuits

Overview

• Flow of Electrons:
  • When the switch is closed, electrons flow out of the cell and move around the circuit.
  • The electric current flows from the negative terminal to the positive terminal.
  • Electrons carry energy from the cell.
  • Energy Transformation:
  • The lamp's electrical energy is converted to light and thermal energy.

Series Circuits

• Characteristics:

  • Series circuits have no branches.
  • The current can only flow in one path.
  • Current Definition:
  • An electric current is a flow of electric charge around a circuit.
  • Unit: ampere (A).

• Measurement:

  • Current is measured using an ammeter.
  • The current is the same all the way around in a series circuit.

Current in Parallel Circuits

Overview

• Parallel Circuits:
  • Contains branches, meaning the current splits.
  • The current in the branches adds up to the total current leaving the cell.