## Details of energy, the definition of energy, a unit of energy, and the relationship between them

**Definition of energy:**

The ability or capability of a body for doing work is known as energy. There are several kinds of forms of energy, but the most important ones are – 1. electrical energy, 2. mechanical energy, and 3. thermal energy.

Now, remember these energies are all interchangeable.

### Unit of energy:

Energy is a measurable quantity so we need to assign units to energies, and as the energies are interchangeable so their unit should also have a relation between them or the same unit can be assigned because the energies are just in different forms.

**1. Electrical Energy: **The SI unit of electrical energy is watt-second also known as joule. Suppose there are two points that have a potential difference of 1 volt now a current of 1 ampere is flowing from one point to another.Â

So Power is equal to 1 volt * 1 ampere =1 watt.

Now if this continues for 1 second, then the energy consumed will be 1 watt * 1 second which is equal to 1 watt-second.Â

In case the system is AC then another factor called power factor comes into the picture,Â

so, watt-second =1 volt * 1 ampere * power factor *1 second.

**2. Mechanical Energy:**

The unit of mechanical energy in the SI system is Newton’s meter also known as the joule. When a force of 1 Newton makes a body move by a 1-meter distance then the work done on the body is 1 joule or 1 Newton meter.

**3. Heat Energy:**

The unit of heat energy in the SI unit is the joule. There are also other units that as calories, British thermal units, or B. Th. U etc. Calories stand for the amount of heat energy that is required to increase the temperature of 1 gram of water by 1 degree centigrade.

similarly, the British thermal unit can be expressed as the heat energy required to increase the temperature of one pound of water by one degree Fahrenheit.

### Relationship between the unit of energy

All three energies as mentioned above are convertible from one form to another, so their units also have a relationship between them, and another thing is there to remember that all three energies can do some work so they should have a common unit, and we can see that all the three energies have a common unit that is “Joule” now let us see the relationship between them.

Relationship between kWhr and Joule

1 kWhr (Unit)

= 1000 watt * 1 hr

=1*10^3 watt*3.6*10^3 sec.

=3.6*10^6 watt- sec= 3.6*10^6 Joule

Relationship between kWhr and N-m

1 N-m = 1 Joule

1 kWhr= 3.6*10^6 Joule

= 3.6*10^6 N-m

Relationship between Calorie and kWhr

1 kWhr=3.6*10^6 Joule

Again,

1 Calorie=4.18 Joule (Experimental value)

So,

1 Joule= 1/4.18 Cal

So,

1 kWhr= 3.6*10^6/4.18 Cal

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I hold a Bachelor of Engineering (BE) degree in Electrical Engineering, which has equipped me with a solid foundation in the principles and applications of electrical technology. Throughout my academic journey, I focused on developing a deep understanding of various electrical systems, circuits, and power distribution networks.