# What is the first law of thermodynamics?

### First Law of Thermodynamics:

The first law of thermodynamics states that the amount of heat given to a system is equal to the sum of the increase in the internal energy of the system and the external work done.

### Explanation

When the whole of the work done is used in producing heat or vice versa then,

W = JH                       [J is the Joule’s mechanical equivalent of heat]

Let,
δH = the quantity of heat
δW = amount of external work done
dU = the increase in internal energy.

Then, mathematically we can write,

δH = dU + δW

The above equation represents the first law of thermodynamics.

## Author: Tanmay Chakrabarty

Tanmay Chakrabarty is a former CSE student, currently working as a Senior Software Engineer with 5+ years of experience in the field of Web Application development in PHP+MySQL platform with strong skills in Javascript, JQuery, JQuery UI and CSS. He tries to write notes every week but fails due to heavy loads of duty.