Electricity

• What must you be able to do regarding circuit diagrams?

  Draw and interpret circuit diagrams
• How is electric charge calculated in a circuit?

  Charge flow = current x time
• What does the resistance of a component measure?

  How it resists the flow of charge
• What is the unit of electric charge?

  Coulombs (C)
• What is the unit of current?

  Amperes (A)
• What is the unit of resistance?

  Ohms (Ω)
• How is potential difference defined in a circuit?

  Difference in electrical potential between two points
• What happens to current when resistance increases?

  Current decreases
• What is the relationship between potential difference, current, and resistance?

  V = IR
• What is the main risk associated with current flowing through a wire?

  It can cause the wire to get hot
• How should an ammeter be connected in a circuit?

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

  In parallel to the component
• What does a straight line through the origin on an I-V graph indicate?

  Potential difference and current are directly proportional
• What does a steep gradient on an I-V graph indicate?

  Low resistance
• What does a shallow gradient on an I-V graph indicate?

  High resistance
• What happens to the resistance of a thermistor as temperature increases?

  Resistance decreases
• What is the effect of adding resistors in series?

  Increases total resistance
• What is the effect of adding resistors in parallel?

  Reduces total resistance
• What is the formula for power in a circuit?

  P = IV
• What does the total potential difference in a series circuit do?

  It is shared between components
• What is the relationship between power, potential difference, and current?

  Power is related to both potential difference and current
• How does the current through a filament lamp change as temperature increases?

  Current decreases as resistance increases
• What are the key differences between series and parallel circuits?

  • Series circuits: same current through each component, total potential difference is shared, total resistance is the sum of resistances.
  • Parallel circuits: potential difference is the same across components, total current is the sum of individual currents, total resistance is less than the smallest resistor.
• What are the characteristics of an ohmic conductor?

  • Current is directly proportional to potential difference at constant temperature.
  • Resistance remains constant as current changes.
  • Indicated by a linear (straight line) graph.
• What are the characteristics of a diode?

  • Current flows in one direction only.
  • Very high resistance in the reverse direction.
  • Indicated by a horizontal line along the x-axis, showing no current flows.
• What are the characteristics of a thermistor?

  • Resistance decreases as temperature increases.
  • Useful for temperature control or response in circuits.
  • Example: used in thermostats or overheating indicators.
• What are the characteristics of a light dependent resistor (LDR)?

  • Resistance decreases as light intensity increases.
  • Useful for automatic light control or detection.
  • Example: used in street lights or cameras to determine flash needs.
• What is the formula to calculate the potential difference across a resistor in a series circuit?

  V = V₁ + V₂
• If a circuit has a 12 V supply and a 4 Ω resistor with 8 V across it, what is the potential difference across the second resistor?

  4 V
• What are the key terms related to electricity that students should know?

  • Current
  • Charge
  • Resistance
  • Potential difference
  • Precision
• What happens to the total resistance when resistors are added in parallel?

  Total resistance decreases
• Why does adding resistors in parallel reduce total resistance?

  More paths for current allow easier flow
• What must you calculate in d.c. series circuits?

  Currents, potential differences, and resistances
• In a series circuit with a 12 V supply and a 4 Ω resistor with 8 V across it, what is the potential difference across the second resistor?

  4 V
• How do you find the potential difference across a resistor in a series circuit?

  Rearrange the equation V = V₁ + V₂
• What is the formula for power in electrical circuits?

  P = IV
• How does power relate to potential difference and current?

  Higher potential difference or current means more power
• If a kettle has an output power of 2300 W at 230 V, what is the current flowing through it?

  10 A
• What can be inferred about the resistance of a resistor if it has a potential difference of 5 V across it in a circuit with a 6 V supply?

  It has a lower resistance than the other resistor
• How do you calculate the total power used by a bulb with a resistance of 6 Ω and a current of 2 A?

  Power = 12 W