Analyse applications of step-up and step-down transformers

  • The loss of energy due to heating up of energy is : H = I2Rt, where
    • I is current in wire,
    • R is resistance of wire
    • and t is time of current flow
  • Thus power loss is P = I2R
  • Power loss can be reduced by reducing current or resistance.
  • Since resistance, over long distance, due to extremely high values of l,  the total resistance of the wire becomes very high and is hard to reduce.
  • We can reduce power loss by reducing current.
  • We use the Step-Up transformers to increase the voltage many times using Ns>Np.
    • equations of transformers, so Vs>Vp
  • equations of transformers, So when Ns>Np , the current Is < Ip
  • Thus with higher voltage being transmitted , the current is reduced
  • Thus power loss is also reduced.
  • Then a step-down transformer is used near households to reduce the voltage to usable amounts.

Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)