electricity

• What is electric current?

  The flow of electric charge around the circuit
• Under what condition will current flow in a circuit?

  When there is a source of potential difference
• What is the unit of current?

  Amps (A)
• How does current behave in a single closed loop circuit?

  The current has the same value everywhere in the circuit
• What is potential difference also known as?

  Voltage
• What is the unit of potential difference?

  Volts (V)
• What does resistance do in a circuit?

  It opposes the current flowing
• What is the unit of resistance?

  Ohms (Ω)
• What factors affect the current flowing through a component?

  The potential difference across it and the resistance of the component
• How does resistance affect current for a given potential difference?

  The greater the resistance, the smaller the current that flows
• What is the formula for charge in a circuit?

  Charge (C) = Current (A) × Time (t)
• What are the units for current, charge, and time?

  Current is in amperes (A), charge is in coulombs (C), and time is in seconds
• What happens to the charge passing through a circuit when a bigger current flows?

  More charge passes around the circuit
• What are the key circuit diagram symbols you need to know?

  • Battery
  • Resistor
  • Light bulb
  • Switch
  • Ammeter
  • Voltmeter
• What is the formula linking potential difference, current, and resistance?

  Potential difference (V) = Current (A) × Resistance (Ω)
• What characterizes ohmic conductors?

  Their resistance stays the same as current changes
• How does the resistance of a filament lamp change with current?

  The resistance increases as the current increases
• How does the resistance of a diode depend on current direction?

  It allows current to flow in one direction but has high resistance in the reverse direction
• What factors can affect resistance in a circuit?

  • Length of the conductor
  • Material of the conductor
  • Temperature
  • Arrangement of components (series or parallel)
• What does an ammeter measure?

  The current flowing through the test wire
• How should an ammeter be connected in a circuit?

  In series with whatever you’re investigating
• What does a voltmeter measure?

  The potential difference across the test wire
• How should a voltmeter be connected in a circuit?

  In parallel around whatever you’re investigating
• What is a light-dependent resistor (LDR)?

  A resistor that depends on the intensity of light
• How does the resistance of an LDR change with light intensity?

  Resistance falls in bright light and is highest in darkness
• What are some applications of LDRs?

  Automatic night lights, outdoor lighting, and burglar detectors
• What is a thermistor?

  A temperature-dependent resistor
• How does the resistance of a thermistor change with temperature?

  Resistance drops in hot conditions and increases in cool conditions
• What are some applications of thermistors?

  Car engine temperature sensors and electronic thermostats
• What are the characteristics of sensing circuits using LDRs and thermistors?

  • Turn on or increase power to components based on conditions
  • Used in applications like fans and automatic lighting
• What is the current behavior in series circuits?

  The same current flows through all components
• How is the size of current determined in series circuits?

  By the total potential difference and total resistance of the circuit
• How do you calculate total resistance in series circuits?

  By summing the resistances of the components
• What happens to the potential difference across each resistor in a series circuit?

  It is lower, leading to a lower current through each resistor
• In a circuit with two resistors of 2Ω and 3Ω in series, what is the total resistance?

  5Ω
• What is the behavior of current in parallel circuits?

  The total current is equal to the sum of the currents through each component
• What happens if one component is removed in a parallel circuit?

  It hardly affects the others
• What is the potential difference across components in parallel circuits?

  It is the same across all components
• How does adding a resistor in parallel affect total resistance?

  It reduces the total resistance of the circuit
• What are the results of adding resistors in series and parallel?

  • Adding resistors in series increases total resistance
  • Adding resistors in parallel decreases total resistance