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PHYSICS · Stage 9 · Chapter 14: Electrical Circuits, Resistance and Power

Physics 14.2 Voltage in series and parallel circuits — Potential Difference and Voltmeters

5 min read 5 parts Lesson 2 of 6

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Physics 14.2 Voltage in series and parallel circuits — Potential Difference and Voltmeters — Alhussan International Academy — Physics (Stages 7–9) notes: Describe voltage, how to measure it and how voltage behaves in series and parallel circuits.Voltage = the push that a cell or …

  • Bigger voltage
  • Connection
  • Across a battery
  • Across a component
  • Lifting charges
  • Factory model

Section 1 of 5What voltage is

  • Voltage = the push that a cell or battery gives to charges, also called potential difference.
  • Energy
    • Voltage tells us the energy transferred to the charge by the battery or by the charge to the components.
  • Bigger voltage
    • The push is bigger.
    • More charge passes a point each second, so the current is bigger.
    • More energy is transferred to components, so lamps are brighter and buzzers louder.
  • Unit
    • Voltage is measured in volts (V).

Section 2 of 5Measuring voltage

  • Voltmeter
    • It measures the voltage across a component.
  • Connection
    • A voltmeter is connected to each side of a component, in parallel, not in series like an ammeter.
  • Across a battery
    • It shows the energy supplied to the charge by the battery.
  • Across a component
    • It shows the energy supplied by the charge to the component.

Section 3 of 5A model for voltage

  • Lifting charges
    • A battery "lifts up" charges, and they "fall back down" through the components, transferring energy to them.
  • Factory model
    • A factory loads a lorry with 6 boxes, like the 6 V of the battery; delivering 3 boxes to each of two shops is like 3 V across each lamp.

Section 4 of 5Voltage in a series circuit

  • Cells in series
    • Their voltages add, so six 1.5 V cells give 9 V.
  • Sharing
    • The voltages across components add up to the voltage of the battery.
  • Different components
    • If the components differ, the voltages across them are different.
  • Reason
    • Energy given to each charge by the battery is shared among the components in turn.

Section 5 of 5Voltage in a parallel circuit

  • Same voltage
    • The voltage across each branch is the same and equals the battery voltage.
  • Direct connection
    • Each branch is connected directly to the battery.
  • Independent
    • Each component works independently of the others.
  • Adding lamps
    • The voltmeter readings stay the same, but the battery is drained faster.
  • Brightness
    • Lamps in parallel are as bright as a single lamp on the same battery.
CircuitVoltage across components
SeriesShared; adds up to the battery voltage
ParallelEach branch has the full battery voltage

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