Find important formulae from unit Heat and Thermodynamics for quick revision. This unit contributes about 10 percent of total questions in any entrance examinations.
When exams are round the corner then it is not possible to revise complete books so we have come up with unit wise formulas and important terms. Once you have gone through chapters thoroughly and understood it well there is no need to study it again and again. You can only revise important formulas and terms which will save your precious time.
In this regard find Heat and Thermodynamics important Formulae for Quick Revision. These formulae will be helpful in various engineering entrance examinations such as IIT JEE, UPSEE, WBJEE etc.
In UPSEE and WBJEE where most of questions are asked directly on formulae, this quick revision note is very important.
Heat and Thermodynamics
- Ideal-gas equation applies not just to a given quantity of a single gas but to any quantity of any dilute gas.
- The increase in the dimensions of a body due to the increase in its temperature is called thermal expansion.
The expansion in length is called linear expansion.
The expansion in area is called area expansion.
The expansion in volume is called volume expansion.
- The change in temperature of a substance, when a given quantity of heat is absorbed or rejected by it, is characterized by a quantity called the heat capacity of that substance.
- Every substance has a unique value for the amount of heat absorbed or rejected to change the temperature of unit mass of it by one unit. This quantity is referred to as the specific heat capacity of the substance.
- Calorimeter is a device in which heat measurement can be made.
- The change of state from solid to liquid is called melting and from liquid to solid is called fusion.
- The boiling point of a substance at standard atmospheric pressure is called its normal boiling point.
- The change from solid state to vapour state without passing through the liquid state is called sublimation.
- Q = mL
where, L = latent heat
- There are three distinct modes of heat transfer: conduction, convection and radiation.
- If a bar with its two ends maintained at temperatures Tc and Td, then steady state heat flow by conduction is given as:
where, K = thermal conductivity
- According to Newton’s law of cooling, the rate of loss of heat, – dQ/dt of the body is directly proportional to the difference of temperature ΔT = (T2–T1) of the body and the surroundings.
- First law of thermodynamics is a law of conservation of energy given by,
P = Pressure
- Work done can also be obtained by area under p-V curve.
- A process in which the temperature of the system is kept fixed throughout is called an isothermal process.
- In isobaric processes the pressure is constant while in isochoric processes the volume is constant.
- If the system is insulated from the surroundings and no heat flows between the system and the surroundings, the process is adiabatic.
- For an ideal gas,
- For any ideal gas,
PV = nRT
- The Second law of thermodynamics says that efficiency of a heat engine can never be unity.