Induced potential, transformers and the national grid

• What happens when a wire moves up through a magnetic field?

  A potential difference is induced
• What happens to the potential difference when the wire stops moving?

  The potential difference disappears
• What happens to the potential difference when the wire moves back down through the magnetic field?

  A potential difference is induced in reverse
• What do scientists call this potential difference?

  The induced potential
• What happens if there is a complete circuit when a potential difference is induced?

  A current is induced
• What is the phenomenon of inducing a current in a complete circuit called?

  The generator effect
• What happens to the direction of the induced current when the direction of movement switches?

  The direction of current switches
• What happens to the induced current when the movement stops?

  The current stops
• What happens if the wire is kept still but the magnetic field moves?

  An induced potential/current occurs
• Under what conditions does the generator effect occur?

  When the wire passes through field
• What happens if the wire moves along the magnetic field?

  No induced potential difference
• What three factors affect the magnitude of the induced potential difference or current?

  Magnetic field, speed, coil turns
• How does the strength of the magnetic field affect the induced potential difference and current?

  Stronger field = larger potential/current
• How does the speed of the wire's movement affect the induced potential difference and current?

  Faster movement = larger potential/current
• What effect does shaping the wire into a coil have on the induced potential difference and current?

  Increases the induced potential/current
• How does the number of turns on the coil affect the induced potential difference and current?

  More turns = larger potential/current
• What happens when a magnet moves in and out of a coil of wire?

  It produces an induced current
• What happens to the direction of the current when the direction of movement of the magnet changes?

  The direction of current changes
• How can the direction of the induced current be switched?

  By switching the poles of magnet
• What key effect is created by the induced current when moving a magnet into a coil of wire?

  It creates its own field
• What does the magnetic field created by the induced current do?

  It opposes magnet's movement
• What happens when the North Pole is pulled out of the coil?

  Coil end becomes a South Pole
• What happens when the North Pole of a magnet is inserted into a coil?

  Coil end becomes a North Pole
• Why does the induced current make it harder to move the magnet?

  It creates an opposing force
• What is happening when it becomes harder to move the magnet in and out of the coil?

  We are doing work
• What energy transfer occurs when moving a magnet near a coil induces a current?

  Magnet movement to current movement
• What is the national grid?

  A giant network of transformers and wires
• What is the purpose of the national grid?

  To distribute electricity across the country
• Where does most of the UK's electricity come from?

  Power stations
• How do power stations generally work?

  Converting thermal energy into electrical energy
• On what does the amount of electricity generated by power stations depend?

  Demand
• When does electricity demand generally peak?

  Late afternoon and evening
• Why do power stations need spare capacity?

  To cope with surges in demand
• What does the national grid have to do due to loads of energy always being used?

  Transmit huge amounts of power
• What is the equation for power?

  Power = voltage * current
• Why is high current flow in wires problematic?

  It generates lots of heat
• What is the effect of the heat generated by high current in wires?

  Energy loss to the surroundings
• How is energy loss due to heat minimized in the national grid?

  By keeping the current really low
• What does keeping the current really low mean for the voltage?

  The voltage will have to be really high
• What type of transformer is used to increase voltage from the power station?

  Step up transformers