Circuits

• 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


  • Resistor with a resistance that is fixed and cannot be changed
• Variable resistor


  • Resistor where the value of the resistance can be changed
• 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


  Electric current that moves in one direction only
• Alternating current


  Electric current that regularly changes direction and size
• Electrical current


  The rate of flow of electric charge
• Direct current


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


  An electric current that regularly changes its direction and size
• When current flows, electrical work is done and energy transferred
• Charge


  A property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative.
• One coulomb of charge is a package equivalent to 6,250,000,000,000,000,000 electrons
• Calculating charge


  • If a current of 1.5 A flows for 60 s, the charge is 90 C

  If a current of 13 A flows for 10 s, the charge is 130 C

  If 10 C passes down a wire in 2 s, the current is 5 A
• Ammeter


  A device used to measure electric current
• 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


  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


  In a parallel circuit, the current divides into two or more paths before recombining to complete the circuit.
• Voltage


  The potential difference across a cell, electrical supply or electrical component. Measured in volts (V).
• When a charge moves through a potential difference

  Electrical work is done and energy transferred
• One volt is the potential difference when one coulomb of charge transfers one joule of energy
• Conductors have a low resistance, insulators have a high resistance
• 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


  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


  In a parallel circuit, the current divides into two or more paths before recombining to complete the circuit.
• Voltage


  The potential difference across a cell, electrical supply or electrical component. Measured in volts (V).
• When a charge moves through a potential difference

  Electrical work is done and energy transferred
• One volt is the potential difference when one coulomb of charge transfers one joule of energy