- Definition of Electrical Energy Unit: The unit of electrical energy is the joule, which is defined as the energy needed to move one-ampere current through one volt in one second.
- Commercial Unit: The commercial unit of electrical energy is the watt-hour, and larger measurements use kilowatt-hours (kWh), which equals 1000 watt-hours.
- Mechanical Energy Relation: Mechanical energy is measured in joules, the same as electrical energy, linking both through their definition and usage.
- Heat Energy Relation: Heat energy is measured in calories, BTUs, and CHUs, with one calorie equivalent to 4.18 joules.
- Electrical Energy Equivalents: Electrical energy equivalents are used to compare and convert electrical energy to common heat energy units like calories and BTUs.
The unit of electric power is watt, and hence unit of electrical energy is watt – second since energy is the product of power and time. The watt – seconds is referred as joules. One joule means the work required to be done for transferring one-ampere current in one second from one point to another point of potential difference one volt. So one-joule electrical energy equals to the product of one volt, one ampere and one second.
A joule, equal to one watt-second, is a very small unit of energy, making it difficult to measure practical electrical energy consumption with it.
Commercial Unit of Electrical Energy
To solve the problem of measuring practical electrical energy consumption, we use a commercial unit called the watt-hour, which is a larger unit of electrical energy.
Another bigger unit of electrical energy is kilowatt-hours or kWh. This equals to 1000 X one watt-hour.
Relation between Unit of Electrical Energy and Unit of Mechanical Energy
A unit of mechanical energy is defined as the amount of work needed to move an object one meter with a force of one newton, called a joule. One joule of electrical energy also equals one watt-second.
Relation between Unit of Electrical Energy and Unit of Heat Energy
Heat is another form of energy commonly used in engineering. Units of heat energy include the calorie, British thermal unit (BTU), and centigrade heat unit (CHU). One calorie is the amount of heat needed to raise the temperature of one gram of water by one degree Celsius.
Practically calorie is a very small unit of heat that is why we often use kilocalorie instead. One kilocalorie is the amount of heat required to raise the temperature of 1 kg of water to 1oC.
British thermal unit is the amount of heat required to raise the temperature of 1 pound of water to 1oF.
Centigrade heat unit is the amount of heat required to raise the temperature of 1 pound of water to 1oC.
The mechanical work to be done for raising the temperature of one gram of water to one degree centigrade is 4.18 joules. We can say one calorie is equivalent to 4.18 joules.
Electrical Energy Equivalent of Centigrade Heat Unit
Electrical Energy Equivalent of British Thermal Unit
