P2: Current, Potential Difference & Resistance Physics GCSE

• What is the purpose of a cell or battery in a circuit?

  Provides a source of potential difference
• What does a switch do in a circuit?

  Turns the circuit on or off
• How does a fixed resistor function in a circuit?

  Limits the flow of current with constant resistance
• What is the role of a variable resistor?

  Changes its resistance using a slider
• How does a thermistor's resistance change?

  Decreases as temperature increases
• What does an LDR do?

  Changes resistance based on light intensity
• What is the function of a diode?

  Allows current to flow in one direction only
• What is a light-emitting diode (LED)?

  Emits light when current passes through it
• What is the purpose of an ammeter?

  Measures the current in a circuit
• How is a voltmeter connected in a circuit?

  In parallel with the component being measured
• What is the significance of the resistance of an ammeter?

  Its resistance is negligible in calculations
• What is the significance of the resistance of a voltmeter?

  Its resistance is considered infinite in calculations
• What are the essential components of an electric circuit diagram?

  • An energy source (cell, battery, power supply)
  • A closed path (complete circuit)
  • Electrical components (sensors, measuring devices, energy transfer devices)
• How should an ammeter be connected in a circuit?

  Always connected in series
• How should a voltmeter be connected in a circuit?

  Always connected in parallel
• What is the direction of current flow in a circuit?

  From positive to negative terminal
• What must be true for a circuit to function?

  The switch must be closed
• What does a forward-biased diode do?

  Allows current to flow in one direction
• What is the symbol for potential difference?

  V
• What is the definition of potential difference?

  Energy transferred per unit charge
• How is potential difference measured?

  Using a voltmeter in parallel
• What is the unit of electric current?

  Amperes (A)
• What is the relationship between charge and current?

  Current is the flow of electrical charge
• What is the unit of charge?

  Coulomb (C)
• How is one coulomb defined?

  Charge passing a point when 1 A flows
• What is the equation relating charge, current, and time?

  Q = It
• How do you calculate current from charge and time?

  I = Q/t
• What is conventional current?

  Flow of positive charge from positive to negative
• Why is current the same at all points in a closed-loop circuit?

  Electrons flow consistently through the circuit
• What is resistance?

  Opposition to current flow in a circuit
• What is the unit of resistance?

  Ohms (Ω)
• How is resistance defined in terms of voltage and current?

  R = V/I
• What happens to current if resistance increases?

  Current decreases for a given voltage
• What is the potential difference across a resistor with 10 Ω resistance and 0.3 A current?

  $3 \text{ V}$
• What is the relationship between current, resistance, and potential difference?

  • Current (I) is directly proportional to potential difference (V)
  • Current (I) is inversely proportional to resistance (R)
  • The equation is V = IR
• What is the formula triangle for current, resistance, and potential difference?

  • V at the top
  • I and R at the bottom
  • V = IR
• What happens when an electron hits the lattice in a wire?

  It transfers energy and slows down
• Why does the wire heat up?

  Due to collisions of electrons with the lattice
• How does the temperature of the wire affect its resistance?

  Higher temperature increases resistance
• What is the formula relating voltage, current, and resistance?

  V = IR