# What is Heat? Definition of heat, basic information related to heat (Heat meaning in hindi)

## What is Heat

“Heat is a form of energy. The feeling of hot or cold of an object is known only by its thermal level i.e. temperature. An object takes more heat when it is hot and less heat when it is cold.

• Heat is measured in calories or joules.
• Where does the calorimeter go to measure the heat?

## Units of heat

The SI unit of heat is the joule, but the following units are also used for this.

### (i) Calorie-

It is necessary to raise the temperature of one gram of water by 1°C.
The amount of heat is called a calorie. 1 calorie of heat is equal to 4.2 joules of work.

### (ii) International Calorie-

International calorie is the amount of heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C.

### (iii) British Thermal Unit (B.Th.U.)-

The amount of heat required to raise the temperature of one pound of water by 1 degree Fahrenheit is called a British thermal unit.

•1 B.Th.U =252 Calorie
•1 Calorie =4.18 joules

## ऊष्माधारिता (Thermal Capacity)-

The amount of heat required to raise the temperature of an object by 1°C is called the heat capacity of the object. Its unit is Calorie/°C or Joule/°C.

heat capacity = mass of the object (m) x specific heat of the substance (s)

## Specific Heat

The amount of heat required to raise the temperature of a unit mass of a substance by 1°C is called the specific heat of that substance.

• It is denoted by S. Its unit is calorie per gram/°C or joule/kg/°C.
Q=sm×dt, s = constant, Q = heat, m = mass, dt = rise in temperature.

## Transmission of Heat in Hindi-

The transfer of heat from one place to another is called transmission of heat. There are three methods of heat transmission.

(i) Conduction
(ii) Convection

(i) Conduction In this method, the molecules of substances without leaving their place give their heat to the adjacent molecules. In solids, heat is transferred by this method.

(ii) Convection-In the method of convection, the molecules of a substance move away from their place by taking heat and other molecules come in their place. This process continues uninterruptedly. This is how heat is transmitted in liquids.

• The transmission of heat in liquids and gases is mainly through the process of convection.

(iii) Radiation.When heat reaches from one place to another without affecting any medium, then this method is called radiation.

• This method of heat transmission does not require a medium. This means that through this medium heat is transmitted in a vacuum.

## Difference between temperature and heat

There is a big difference between the temperature of an object and the heat contained in it. The heat contained in an object depends on the mass and temperature of that object.

blacksmith’s hammer Spark Hand does not burn when it is at very high temperature. This happens because the mass of the spark is very (Heat in hindi)is less, as a result of which very little amount of heat is contained in it,

Whereas a jug of hot water whose temperature is much lower than that of the spark, a burning sensation is felt in the hand, because its mass is much greater than that of the spark, as a result, a greater amount of heat is contained in it.

Earlier it was believed that heat was a kind of liquid, which “Caloric” used to say and Matter The space between the molecules of the substance was filled, and when the temperature of the object was high, it was believed that a large amount of this liquid was stored in it. to this principle “Caloric Theory of Heat” Used to say But this theory could not explain many events later and was rejected.

Heat is a form of energy that can be converted into work. First of all direct evidence of this रमफोर्ड (Rumford) gave. Later Davy They melted two ice cubes by rubbing them together. Since there was no other source of heat to melt the ice, it was assumed that the work done in rubbing the ice was converted into the heat required to melt the ice. Joule later confirmed with his experiments that “heat is a form of energy.”

Whenever work changes into heat, or heat changes into work, the ratio of work done and heat generated is a constant, which is called the “mechanical equivalent of heat”. It is represented by j.

If Q is the amount of heat from doing W work, then

•W=JQ, J=4186 is joule/kilocalorie. This means that if 4186 joules of mechanical work is done, the amount of heat generated will be 1 kilocalorie.

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