Calculating Energy Transferred by Appliances

• What do power ratings indicate about appliances?

  They show energy transferred per second
• How do you calculate total energy transferred using power ratings?

  Multiply power by time
• How do you convert joules to kilojoules?

  Divide by 1,000
• How do you calculate energy transferred for a fan with a power rating of 20 watts used for 1 hour?

  Multiply 20 by 3,600
• How do you convert 5 minutes to seconds for the iron's energy calculation?

  Convert to 300 seconds
• How do you calculate the power of the iron given 600,000 joules transferred in 5 minutes?

  Divide 600,000 by 300
• How do you calculate the time the blender is used if it transfers 48,000 joules at 400 watts?

  Divide 48,000 by 400
• What is the equation for calculating energy transferred by electrical appliances?

  • Energy (joules) = Power (watts) × Time (seconds)
• What are the steps to calculate energy transferred by an appliance?

  1. Identify power rating in watts
  2. Convert time to seconds if necessary
  3. Use the equation: Energy = Power × Time
• What are the common units for energy and power in electrical appliances?

  • Energy: Joules (J) or Kilojoules (kJ)
  • Power: Watts (W)