first law of thermodynamics

First law of thermodynamics states that, “If a system passes through a cycle of processes so that it returns to its initial state the sum of heat and work effects will be zero.

1. First law of thermodynamics states: Heat and work are mutually convertible but since energy can neither be     created no destroyed; the total energy associated with an energy conversion remains constant

                                                                 OR

 No machine can produce energy without corresponding expenditure of energy, i.e. it is impossible to construct a perpetual motion machine of first kind.

• First law of thermodynamics can be expressed as follows

Q = W + dE = W + dU …. if electric, magnetic, chemical, potential and kinetic    energies are neglected.

• Specific heat of a substance may be defined as the amount of heat required to raise the temperature of unit mass of the substance through one degree.
• The processes occurring in a closed system which do not permit the transfer of mass across their boundaries are known as non flow processes