Electrical Energy | Physics for GCSE/IGCSE - Year 11 PDF Download

Electrical Energy Equation

• Everyday appliances utilize electrical energy from the mains to transform it into various forms of energy within the device. 
  • For instance, in a heater, electrical energy is converted into thermal energy stored within the appliance.
• The quantity of energy transferred by an appliance hinges on two key factors:
  • The duration for which the appliance remains operational.
  • The power rating of the appliance.
• A 1 kW iron consumes the same amount of energy in one hour as a 2 kW iron consumes in just 30 minutes. 
• Similarly, a 100 W heater expends an equivalent amount of energy in 30 hours compared to a 3000 W heater, which consumes the same energy in merely one hour.

Calculating Electrical Energy

• To calculate electrical energy usage, one can utilize the formula:
  
• Where,
  • E = energy (joules, J)
  • V = voltage (volts, V)
  • I = current (amps, A)
  • t = time (seconds, s)

Energy Transfer in Electrical Circuits

• When electricity flows through a circuit, energy is transmitted from the power source to different components. This energy can then be further transferred to the surroundings.
  • As the electric charge moves through the power supply, it gains energy.
  • However, as it passes through individual components, it loses some of this energy, which is then transferred to the component itself.

Different Energy Transfers in Domestic Appliances

• Domestic appliances can draw energy from batteries like those in remote controls.
• Most household appliances derive their power from the AC mains supply.
• Energy from these sources can be converted into kinetic energy within an electric motor.

Motors in Various Appliances

• Vacuum cleaners use motors to create suction for cleaning carpets.
• Washing machines employ motors to rotate the drum for washing or drying clothes.
• Refrigerators utilize motors to compress refrigerant chemicals, lowering temperatures.

Heating Functions

• Heating is employed in devices such as toasters, kettles, and radiators.

Appliance Uses

• Toasters: Used for toasting bread.
• Kettles: For boiling water.
• Radiators: Heat rooms by circulating hot water from a boiler.