P2

• What is an electrical circuit?

  A closed loop with a power source and a path for electrons
• What is the simplest type of circuit?

  A circuit with a cell and a wire
• What is the symbol for a cell in a circuit diagram?

  A long line and a short line
• What is the symbol for a battery in a circuit diagram?

  Two cell symbols put together
• What is the symbol for a filament lamp in a circuit diagram?

  A small light bulb
• What happens when a switch in a circuit is closed?

  Current continues to flow, and the light stays on
• What happens when a switch in a circuit is open?

  Current stops flowing, and the light turns off
• What is current denoted by in circuit diagrams?

  The letter I
• What is the unit of measurement for current?

  Amperes (amps)
• What is potential difference in a circuit?

  The force driving the flow of electrons
• What is potential difference denoted by in circuit diagrams?

  The letter V
• What is the unit of measurement for potential difference?

  Volts
• What is resistance in a circuit?

  Everything that opposes the flow of electrons
• What is resistance denoted by in circuit diagrams?

  The letter R
• What is the unit of measurement for resistance?

  Ohms
• Which terminal of a cell is represented by the longer line in a circuit diagram?

  Positive terminal
• Which terminal of a cell is represented by the shorter line in a circuit diagram?

  Negative terminal
• In which direction do electrons flow in a circuit?

  From the negative terminal to the positive terminal
• What is conventional current?

  Current flowing from positive to negative terminal
• What are the key terms in circuit analysis?

  • Current (I): Flow of electrons, measured in amperes (amps)
  • Potential difference (V): Force driving electrons, measured in volts
  • Resistance (R): Opposition to electron flow, measured in ohms
• What are the main components of a simple circuit?

  • Power source (cell or battery)
  • Conductive path (wire)
  • Load (e.g., filament lamp)
  • Switch (optional)
• What are the symbols for common circuit components?

  • Cell: Long and short lines
  • Battery: Two cell symbols
  • Filament lamp: Small light bulb
  • Switch: Open or closed line
• What is the difference between electron flow and conventional current?

  • Electron flow: Electrons move from negative to positive terminal
  • Conventional current: Current flows from positive to negative terminal
• If a circuit has a potential difference of 12V and a resistance of 4Ω, what is the current?

  $3 \text{ A}$
• If a circuit has a current of 2A and a resistance of 5Ω, what is the potential difference?

  $10 \text{ V}$
• If a circuit has a potential difference of 9V and a current of 3A, what is the resistance?

  $3 \text{ Ω}$
• Why is conventional current still used despite electrons flowing from negative to positive?

  Historical convention established before electron flow was understood
• How does resistance affect the flow of current in a circuit?

  Higher resistance reduces the flow of current
• How does potential difference affect the flow of current in a circuit?

  Higher potential difference increases the flow of current
• If a circuit has a potential difference of 6V and a current of 2A, what is the power?

  $12 \text{ W}$
• If a circuit has a power of 20W and a current of 4A, what is the potential difference?

  $5 \text{ V}$
• What is a parallel circuit?

  A circuit with more than one loop
• What is the national grid?

  A network of transformers and wires distributing electricity
• What are the two types of current discussed in the study material?

  Alternating current (AC) and direct current (DC)
• What is the voltage of the main supply in the UK?

  230 volts
• What is the definition of charge?

  A measure of the total current that flowed within a certain period of time
• What is the primary source of electricity in the UK?

  Power stations
• Why are parallel circuits more useful than series circuits?

  If one component breaks, the overall circuit remains intact
• If a circuit has a power of 30W and a potential difference of 10V, what is the current?

  $3 \text{ A}$
• What is a sudden increase in current called?

  Surge