Power

• 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)
• Calculating power of resistor

  • Potential difference = 50 volts
  • Current = 0.2 amperes
  • Power = 50 x 0.2 = 10 watts
• Calculating power of resistor A

  • Potential difference across resistor A = 5 volts
  • Current = 0.5 amperes
  • Power = 5 x 0.5 = 2.5 watts
• Calculating power using current and resistance

  Use equation: Power (watts) = Current^2 (amperes^2) x Resistance (ohms)
• Calculating power of resistor

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