Electricity

• What is the definition of electric current?

  Electric current is the flow of electrical charge.
• What is required for electrical charge to flow in a circuit?

  A source of potential difference is required.
• In a single, closed loop circuit, what can be said about the current?

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

  Potential difference is also known as voltage.
• What is the unit of potential difference?

  The unit of potential difference is the volt, V.
• What does resistance do in a circuit?

  Resistance slows the flow of electrical charge.
• What is the relationship between current, potential difference, and resistance?

  The current depends on the potential difference and resistance of the component.
• What is the formula for calculating total charge in a circuit?

  Q = I t
• If a current of 2.0 A flows for 2.5 hours, how much charge is transferred?

  Q = 18,000 C
• What is the purpose of circuit diagram symbols?

  Circuit diagram symbols are used to represent components in a circuit.
• How do you draw a circuit diagram for a lamp connected to a power source?

  Draw a closed loop with the lamp and power source connected.
• What happens to the current in a series circuit if one component is removed?

  The circuit breaks and all components stop functioning.
• How is potential difference distributed in a series circuit?

  The total potential difference is shared among the components.
• What is the formula for total resistance in a series circuit?

  R_total = R₁ + R₂ + ...
• If a circuit has a total resistance of 5 Ω and a potential difference of 10 V, what is the current?

  I = 2 A
• What is the effect of adding resistors in series on total resistance?

  Total resistance increases when resistors are added in series.
• What is the difference between alternating current (ac) and direct current (dc)?

  Ac current changes direction, while dc current flows in one direction.
• What is the frequency of the UK mains supply?

  The frequency is 50 Hz.
• What is the typical voltage of the UK mains supply?

  The typical voltage is around 220 V.
• What is the purpose of an ammeter in a circuit?

  An ammeter measures the current flowing through a component.
• How should an ammeter be connected in a circuit?

  An ammeter must be placed in series with the component being investigated.
• What is the purpose of a voltmeter in a circuit?

  A voltmeter measures the potential difference across a component.
• How should a voltmeter be connected in a circuit?

  A voltmeter must be placed in parallel around the component being investigated.
• What happens to the resistance of a filament lamp as the current increases?

  The resistance of the filament lamp increases as the current increases.
• What is an LDR and how does it work?

  An LDR is a resistor that changes resistance based on light intensity.
• What happens to the resistance of an LDR in bright light?

  The resistance of an LDR is low in bright light.
• What happens to the resistance of an LDR in darkness?

  The resistance of an LDR is highest in darkness.
• What is a thermistor and how does it work?

  A thermistor is a resistor that changes resistance based on temperature.
• What happens to the resistance of a thermistor in hot conditions?

  The resistance of a thermistor drops in hot conditions.
• What happens to the resistance of a thermistor in cold conditions?

  The resistance of a thermistor increases in cold conditions.
• How do LDRs and thermistors function in sensing circuits?

  They control the power to components based on environmental conditions.
• What is the effect of adding resistors in parallel on total resistance?

  Total resistance decreases when resistors are added in parallel.
• What happens to the total current in a parallel circuit when more resistors are added?

  The total current through the circuit increases when more resistors are added.
• What is the difference between series and parallel circuits?

  Series circuits have the same current through all components, while parallel circuits have different currents.
• What is the typical voltage of a battery supply?

  A battery supply typically provides direct current (dc).
• What is the purpose of the three separate wires in most electrical cables?

  They provide a safe and effective way to connect electrical appliances.
• What are the two types of electricity supply?

  Alternating current (ac) and direct current (dc)
• How does alternating current (ac) differ from direct current (dc)?

  Ac current changes direction, while dc current flows in the same direction
• What is the voltage of the UK mains supply?

  Approximately 220 V
• What is the frequency of the UK mains supply?

  50 Hz