2.3.4 Power Ratings

Cards (13)

  • Power
    The rate at which energy is transferred or converted; tells us how much energy is used per unit of time
  • Power variables
    • P (Power in watts, W)
    • E (Energy transferred in joules, J)
    • t (Time taken in seconds, s)
  • Watt (W)
    1 watt equals 1 joule per second (J/s)
  • Power rating
    Indicates the maximum power an appliance can use when operating at its highest setting
  • Calculating energy use
    E=P×t
  • Energy consumption variables
    • E (Energy in joules, J or kilowatt-hours, kWh)
    • P (Power in watts, W or kilowatts, kW)
    • t (Time in seconds, s or hours, h)
  • Electricity costs
    Energy companies charge for electricity based on energy use, usually in kilowatt-hours (kWh)
  • Calculating cost of electricity
    Cost=Energy used (kWh)×Cost per kWh
  • Importance of power ratings
    • Safety: Prevents overloading circuits
    • Efficiency: Helps choose energy-efficient appliances
    • Performance: Indicates performance level of an appliance
  • Efficiency
    Not all energy consumed by an appliance is used effectively; some energy is wasted, often as heat
  • Calculating efficiency
    Efficiency=Useful Power Output/Total Power Input×100%
  • Practical examples of power ratings
    • Light Bulb: 60 W
    • Kettle: 2000 W (2 kW)
    • Television: 150 W
  • Understanding power ratings is essential for making informed choices about energy use, safety, and efficiency in everyday life