Electric Energy

• • P=VI
  • P=I²R
  • P=V²/R


  Power(W) = energy(J)/time(S)


  How to measure Power
• watts (W)


  What is the unit for power
• energy(J) = power(W) x time(S)


  How to measure energy
• 1. I=V/R = 15/10=1.5A
  2. P=VI = 15x1.5=22.5W
  3. E=Pt = 22.5x25=562.5J


  Calculate the energy dissipated in a 10Ω resistor when connected to a 15V supply for 25s

  Using: P=VI
• 1. P=V²/R
= 15²/10=22.5W
  2. E=Pt = 22.5x25=562.5J

  Another way is: E=V²xt/R = 15²x25/10 = 2625/10 = 262.5J


  Calculate the energy dissipated in a 10Ω resistor when connected to a 15V supply for 25s

  Using: P=V²/R
• 1. I=V/R = 15/10 = 1.5A
  2. P=I²R = 1.5²x10 = 22.5W
  3. E=Pt = 22.5x25 = 562.5J

  Another way is: E=I²Rt = 1.5²x10x25 = 562.5


  Calculate the energy dissipated in a 10Ω resistor when connected to a 15V supply for 25s

  Using: P=I²R