current, potential difference and resistance

• What does a cell or battery provide in a circuit?

  A source of potential difference
• What is the function of a switch in a circuit?

  To turn the circuit on or off
• What happens to the resistance of a thermistor as temperature increases?

  The resistance decreases
• What does a fixed resistor do?

  Limits the flow of current
• How does a variable resistor differ from a fixed resistor?

  A variable resistor can change its resistance
• How does light intensity affect the resistance of an LDR?

  Resistance decreases as light intensity increases
• What is the primary function of a diode?

  Allows current to flow in one direction
• When does current flow through a diode?

  When it is in forward bias position
• What is the purpose of a light-emitting diode (LED)?

  Emits light when current passes through
• Where is an ammeter connected in a circuit?

  In series with other components
• What is the function of a voltmeter?

  Measures potential difference across a component
• How should a voltmeter be connected in a circuit?

  In parallel with the relevant component
• What is the significance of the resistance of ammeters and voltmeters in exam questions?

  They are considered negligible
• What are the essential components of an electric circuit diagram?

  • An energy source (cell, battery, power supply)
  • A closed path or complete circuit
  • Electrical components (sensors, measuring devices, energy transfer devices)
• What is required for a current to flow in a circuit?

  A complete loop or closed path
• What is the direction of current flow in a circuit?

  From positive to negative terminal
• What are the key rules for connecting ammeters and voltmeters in a circuit?

  • An ammeter is always connected in series
  • A voltmeter is always connected in parallel
• What is required for electrical charge to flow through a closed circuit?

  A source of potential difference
• What are the sources of potential difference?

  • A cell
  • Batteries (multiple cells)
  • Electrical generator
• How does a cell affect the circuit?

  It makes one end positive and the other negative
• What does the potential difference across a circuit set up?

  A voltage across the circuit
• What is the symbol for potential difference?

  V
• How is potential difference defined across a component in a circuit?

  Energy transferred per unit charge flowing
• What can the energy transferred also be called?

  Work done
• What is the equation to calculate potential difference?

  $V =$$\frac{W}{Q}$
• In what unit is potential difference measured?

  Volts (V)
• What is the relationship between volts and joules per coulomb?

  1 V = 1 J C^-1
• If a bulb has a voltage of 3 V, how much energy does each coulomb lose?

  3 J of energy
• How is potential difference measured?

  Using a voltmeter
• How should a voltmeter be set up to measure potential difference?

  In parallel to the component
• How can potential difference be measured in a circuit?

  • Connect a voltmeter in parallel
  • Place it between two points in the circuit
• What is electric current?

  The flow of electrical charge
• In what units is electric current measured?

  Amperes (A) or amps
• What is the symbol for electric current?

  I
• How is the size of electric current defined?

  Rate of flow of electrical charge
• What does the size of electric current indicate?

  How much charge passes a point each second
• What type of charge flows in metals like copper wire?

  Electrons
• What causes the current in a circuit made of metals?

  A flow of electrons
• What is the unit of charge?

  Coulomb (C)
• How is the Coulomb defined?

  Charge passing a point per second at 1 A