Power of components

• Power


  The rate at which energy is transferred
• Watt


  The unit of power, equal to an energy transfer of 1 Joule per second
• Calculating power in an electrical circuit

  1. Know potential difference across component

  2. Know current flowing through component

  3. Use equation: Power (watts) = Potential Difference (volts) x Current (amperes)
• The equation for calculating power in an electrical circuit is: Power (watts) = Potential Difference (volts) x Current (amperes)
• Calculating power of a resistor

  • Given: Potential Difference = 50 volts, Current = 0.2 amperes
  • Power = 50 volts x 0.2 amperes = 10 watts
• Calculating power of a resistor

  • Given: Potential Difference across Resistor A = 5 volts, Current = 0.5 amperes
  • Power = 5 volts x 0.5 amperes = 2.5 watts
• If you know the current through a component and the resistance, you can calculate power using: Power = Current^2 x Resistance
• Calculating power of a resistor

  • Given: Current = 0.4 amperes, Resistance = 50 ohms
  • Power = 0.4^2 x 50 = 8 watts