topic 13 electromagnetic induction

• what is national grid?

  system which transfers electricity from power stations to houses
• why do we need to make energy transfers of national grids efficient as possible?

  make sure there cool and don't waste energy as thermal
• voltage from power station is 10,000V this goes to step up trasnformer and output voltage increases to 400,000V and decreases current in wires
• advantages = small currents don't waste energy

  disadvantage= higher voltage is dangerous
• why is the wires so above the ground

  so dangerous so people can't touch them
• near the homes we have step down transformer which reduces voltage to safer 230V and increases current
• power = current^2 x resistance
• what do step up transformers do?

   increase the voltage in the secondary coil.
• what to step down do?

  decrease the voltage in the secondary coil.
• .

  Step-up transformers have more turns on the secondary coil than the primary coil.

  Step-down transformers have more turns on the primary coil than the secondary coil.
• What can transformer do?

   change the size of an alternating voltage.