Electricity

• What are the main energy resources available on Earth?

  Fossil fuels, nuclear fuel, bio-fuel, wind
• What defines a renewable energy resource?

  It can be replenished as it is used
• What are the uses of energy resources?

  Transport, electricity generation, heating
• What should students be able to do regarding energy sources?

  • Describe main energy sources
  • Distinguish renewable from non-renewable
  • Compare uses of different energy resources
  • Understand reliability of energy resources
  • Describe environmental impacts of energy resources
  • Explain patterns and trends in energy use
• Why are some energy resources considered more reliable than others?

  Due to their availability and consistency
• What environmental issues may arise from energy resource use?

  Pollution, habitat destruction, resource depletion
• What is electric charge?

  A fundamental property of matter everywhere
• What is the relationship between charge flow, current, and time?

  Charge flow = current × time
• What is the unit of electric charge?

  Coulombs (C)
• How does current behave in a closed loop circuit?

  It has the same value at any point
• What does the current through a component depend on?

  Resistance and potential difference across it
• What is the equation for potential difference?

  Potential difference = current × resistance

  
• What is the unit of potential difference?

  Volts (V)
• What happens to the resistance of a filament lamp as temperature increases?

  The resistance increases
• How does a diode behave in a circuit?

  Current flows in one direction only
• What happens to the resistance of a thermistor as temperature increases?

  The resistance decreases
• What is the function of an LDR in a circuit?

  It switches lights on when it gets dark
• What are the characteristics of series circuits?

  • Same current through each component
  • Total potential difference is shared
  • Total resistance is the sum of individual resistances
• What is the equation for total resistance in series?

  Rtotal = R1 + R2
• What are the characteristics of parallel circuits?

  • Same potential difference across each component
  • Total current is the sum of individual currents
  • Total resistance is less than the smallest resistor
• What is the frequency of mains electricity in the UK?

  50 Hz
• What is the voltage of the domestic electricity supply in the UK?

  About 230 V
• What is the purpose of the earth wire in a three-core cable?

  To stop the appliance becoming live
• What is the equation for power in a circuit?

  Power = potential difference × current
• What is the unit of power?

  Watts (W)
• How is energy transferred by electrical work calculated?

  Energy transferred = power × time
• What is the unit of energy transferred?

  Joules (J)
• What is the National Grid?

  • A system of cables and transformers
  • Links power stations to consumers
  • Transfers electrical power efficiently
• What do step-up transformers do in the National Grid?

  Increase potential difference for transmission
• What happens when insulating materials are rubbed together?

  They become electrically charged
• What happens to two objects with the same charge?

  They repel each other
• What is static electricity?

  Electric charge produced by rubbing materials
• How can the transfer of electrons explain static electricity?

  It causes attraction or repulsion between objects
• What is the Hidden Name?

  .

  A) Open Switch

  
• Explain the advantage of transmitting electricity at a very high potential difference. (4)

  • Very high P.D means there's very low current
  • Less thermal energy is transferred to surroundings
  • Less power loss
  • Which Increases efficiency of power transmission
• The current through an ohmic conductor is directly proportional to the Potential Difference across the component, provided

  that the Temperature remains constant.