The national grid

• What is the national grid?

  A web of wires distributing electricity
• How does the national grid function?

  It connects power stations to consumers
• What does the national grid transfer?

  Electrical power from power stations
• What happens to electricity demand throughout the day?

  It changes based on user activity
• Why do power stations run below maximum output?

  To have spare capacity for high demand
• When does electricity demand typically peak?

  Morning, evening, and during events
• What is done with smaller power stations?

  They are kept on standby for emergencies
• How has the national grid evolved since the 1930s?

  It has changed to meet increasing demands
• What is one way to balance supply and demand?

  Switch off unnecessary lights
• What technology does the national grid use for efficient electricity transfer?

  Transformers
• Why is a high potential difference used in the national grid?

  To reduce energy loss during transmission
• What is the high potential difference used in the national grid?

  400,000 V
• What happens to energy when high current is used?

  Energy is lost as heat in wires
• How does increasing potential difference affect current?

  It decreases current for the same power
• What is the role of transformers in the national grid?

  To step up and step down potential difference
• What type of transformer increases potential difference?

  Step-up transformer
• What type of transformer decreases potential difference?

  Step-down transformer
• How efficient are transformers?

  Almost 100% efficient
• How can the relationship between power, potential difference, and current be expressed mathematically?

  Using $P =$$VI$
• What does the equation $VI₁ =$$VI₂$ represent?


  Power conservation in transformers
• What is the primary function of the national grid?

  To distribute electricity efficiently