Electrical energy is the energy derived from the movement of electrons in an electric conductor, typically in the form of electric current. It is a type of energy associated with the flow of electric charge.
Electrical Energy=Voltage×Current×Time
The unit of electrical energy is the watt-hour (Wh) or kilowatt-hour (kWh).
Examples
1. Turning on a Light Bulb:
- A typical household light bulb might operate at
V=120 V and I=0.5 A. - If the light bulb is on for 2 hours, the electrical energy consumed would be
E=V×I×t=120 V×0.5 A×2 h =120Wh.
2. Charging a Smartphone:
- The charging adapter for a smartphone may operate at V=5 V and I=1 A.
- If it takes 1 hour to charge the smartphone, the electrical energy used would be
E=V×I×t=5 V×1 A×1 h =5Wh.
3. Running an Electric Fan:
- An electric fan might operate at V=220 V and I=0.8 A
- If the fan runs for 3 hours, the electrical energy consumed would be E=V×I×t=220 V×0.8 A×3 h=528 Wh =528Wh.
4. Using a Microwave Oven:
- A microwave oven may operate at V=120 V and I=10 A.
- If the microwave is used for 0.5 hours, the electrical energy used would be
E=V×I×t=120 V×10 A×0.5 h=600 Wh
5. Charging an Electric Vehicle:
- Charging an electric vehicle could involve V=240 V and I=30 A.
- If it takes 8 hours to charge, the electrical energy consumed would be E=V×I×t=240 V×30 A×8 h=57,600 Wh
6. Running an Air Conditioner:
- An air conditioner may operate at V=230 V and I=15 A
- If the air conditioner runs for 4 hours, the electrical energy consumed would be E=V×I×t=230 V×15 A×4 h=13,800 Wh
7. Using an Electric Kettle:
- An electric kettle might operate at V=120 V and I=12 A.
- If it takes 0.25 hours to boil water, the electrical energy used would be E=V×I×t=120 V×12 A×0.25 h=360 Wh
8. Operating a Television:
- A television may operate at V=110 V and I=5 A
- If the TV is on for 6 hours, the electrical energy consumed would be E=V×I×t=110 V×5 A×6 h=3,300 Wh
9. Powering an Electric Drill:
- An electric drill might operate at V=18 V and I=8 A
- If the drill is used for 0.5 hours, the electrical energy used would be E=V×I×t=18 V×8 A×0.5 h=72 Wh
10. Running an Electric Heater:
- An electric heater may operate at V=240 V and I=12 A
- If the heater is on for 3 hours, the electrical energy consumed would be E=V×I×t=240 V×12 A×3 h=8,640 Wh
