Electricity

• current 


  the flow of electric charge round the circuit, only flows around a closed circuit if their potential difference
• Potential difference 


  is the driving force that pushes the charge round
• Resistance 


  Anything in the circuit which slows the flow down
• what is a light dependant resistor (LDR)


  a resistor depending on the intensity of light. In a bright light resistance falls, in darkness resistance is highest. LDRs are used in outdoor lighting, burglar detectors
• what is a thermistor 


  A temperature dependant resistor. in hot conditions the resistance drops, in cool conditions resistance increases. they are often used in car engines
• What components can be used in sensing circuits?

  LDRs and thermistors
• How is the potential difference shared in a series circuit?

  The potential difference of the power supply is shared between the components.
• What happens to the resistance of a thermistor as the room gets hotter?

  The resistance of the thermistor decreases as the room gets hotter.
• What effect does a decrease in thermistor resistance have on the potential difference across the fixed resistor and fan?

  The potential difference across the fixed resistor and fan rises, making the fan go faster.
• How can you connect a component across a variable resistor?

  You can connect the component across the variable resistor instead of across the fixed resistor.
• What happens to the potential difference across an LDR and a bulb when it’s dark?

  The potential difference across both the LDR and the bulb will be high when it’s dark and the LDR’s resistance is high.
• How does the brightness of a bulb connected across an LDR change as the room gets darker?

  The bulb connected across an LDR would get brighter as the room got darker.
• What are the key properties of sensing circuits that utilize thermistors and LDRs?

  • React to changes in the surroundings
  • Useful applications of thermistors and LDRs
  • Rely on properties of series and parallel circuits
• Why can sensing circuits be tricky to understand?

  They can be tricky to make sense of due to their reliance on series and parallel circuit properties.
• What is the relationship between potential difference and energy received by a component?

  The greater the potential difference across a component, the more energy it gets.
• How are components connected in a series circuit?

  They are connected in a line, end to end.
• What happens if one component is removed from a series circuit?

  The circuit is broken, and current cannot flow.
• Why is it generally not handy to have many components connected in series?

  Because removing one component breaks the entire circuit.
• What rules can be used to design series circuits?

  • Use to measure quantities
  • Test components
  • Refer to test circuits on specific pages
• What happens to the potential difference when more cells are connected in series?

  The potential difference increases if the cells are connected the same way.
• What is the total voltage supplied by two 1.5V batteries connected in series?

  3V
• How is the total potential difference shared in a series circuit?

  It is shared between the various components.
• What is the formula for the total potential difference in a series circuit?

  V_total = V₁ + V₂ + ...
• What are the two main types of circuits?

  Series and parallel circuits.
• Where should ammeters be connected in a circuit?

  Ammeters should always be connected in series.
• Where should voltmeters be connected in a circuit?

  Voltmeters should always be connected in parallel.
• Do ammeters and voltmeters count towards defining a circuit?

  No, they do not count towards how you define a circuit.
• Can you have a parallel circuit with ammeters connected in series?

  Yes, you can have a parallel circuit with ammeters connected in series.
• Can you have a series circuit with voltmeters connected across components?

  Yes, you can have a series circuit with voltmeters connected across components.
• What is the current flow in series circuits?

  The same current flows through all components.
• How is the size of the current in a series circuit determined?

  It is determined by the total resistance and the total potential difference.
• How do you calculate the total resistance in a series circuit?

  The total resistance is the sum of the individual resistances.
• Why does adding extra resistance in a series circuit affect current flow?

  It makes the current flow less easily.
• What happens to the potential difference across each resistor in a series circuit?

  The potential difference across each resistor is less, leading to less current through each resistor.
• How does the total current behave in a series circuit with multiple resistors?

  The total current is split between each resistor.
• What is the relationship between a component's resistance and its share of the total potential difference?

  The bigger a component's resistance, the bigger its share of the total potential difference.
• How do you calculate the current passing through a circuit with two resistors in series?

  First find the total resistance, then use $V =$$IR$ to calculate the current.
• How are components connected in parallel circuits?

  Components are connected to each other in parallel.
• What happens if one component in a parallel circuit is disconnected?

  The other components will still function normally.
• Why do parallel circuits allow components to function independently?

  Each component has its own path for current flow.