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• Electrical circuit symbols


  Symbols that show the different components that can be found in an electrical circuit
• Common electrical circuit components

  • Switch
  • Lamp
  • Fixed resistor
  • Variable resistor
  • Thermistor
  • Light-dependent resistor (LDR)
  • Semiconductor diode
• Switch


  • Used to turn a circuit on (closed) and off (open)
• Lamp


  • Electrical current heats the filament causing it to emit heat and light
• Fixed resistor


  • Resistance that is fixed and cannot be changed
• Variable resistor


  • Resistance can be changed by moving the position of the slider
• Thermistor


  • Resistance decreases as temperature increases
• Light-dependent resistor (LDR)


  • Resistance decreases as light intensity increases
• Semiconductor diode


  • Allows current to flow in one direction only
• Electrical current transfers energy around circuits
• Direct current


  Movement of charge through a conductor in one direction only
• Alternating current


  Electric current that regularly changes its direction and size
• Electrical current


  The rate of flow of electric charge
• When current flows, electrical work is done and energy transferred</b>
• Charge


  Property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative.
• Direct current


  • The flow of electrons is consistently in one direction around the circuit
• Alternating current


  • The direction of electron flow continually reverses
• Electrical current transfers energy around circuits
• There are two types of current: direct and alternating
• To measure the current through a component, the ammeter must be placed in series with that component
• Electrical current


  Transfers energy around circuits
• Types of current


  • Direct
  • Alternating
• Resistance


  The opposition in an electrical component to the movement of electrical charge through it. Measured in ohms.
• Potential difference (voltage)


  The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V).
• Voltmeter


  A device used to measure potential difference or voltage.
• Parallel circuit


  In a parallel circuit, the current divides into two or more paths before recombining to complete the circuit. Lamps and other components in these different paths are said to be in parallel.
• When a charge moves through a potential difference

  1. Electrical work is done

  2. Energy is transferred
• Conductors have a low resistance. Insulators have a high resistance.
• Resistance


  The opposition in an electrical component to the movement of electrical charge through it. Resistance is measured in ohms.
• Potential difference


  The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them.
• Current


  Moving electric charges, eg electrons moving through a metal wire.
• Ammeter


  A device used to measure electric current.
• Voltmeter


  A device used to measure potential difference or voltage.
• Voltage


  The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V).
• Electrical current


  Transfers energy around circuits
• Types of current


  • Direct
  • Alternating
• Electrical current transfers energy around circuits
• Series circuits


  • Electrical components are connected one after another in a single loop
  • An electron will pass through every component on its way round the circuit
  • If one of the bulbs is broken then current will not be able to flow round the circuit
  • If one bulb goes out, they all go out
• Current in series circuits

  • All electrons in that loop form one current
  • An ammeter will measure the same current wherever it is placed in the circuit
• Potential difference in series circuits

  The potential difference supplied is equal to the total of the potential differences across all other components