1st Year Physics Chapter 11 Notes

• Important 1st year physics chapter 11 mcqs from Punjab Textbook.
• Kinetic theory of gases and Postulates of Kinetic theory of gases: The behavior of gases is well accounted for by the kinetic. theory based on microscopic approach. Evidence in favour of the theory is exhibited in diffusion of gases and Brownian motion of smoke particles etc. The following postulates help to formulate a mathematical model of gases. A finite volume of gas consists of very large number of molecules. The size of the molecules is much smaller than the separation between molecules. The gas molecules are in random motion and may change their direction of motion after every collision. iv. Collision between gas molecules themselves and with walls of container are assumed to be perfectly elastic. V. Molecules do not exert force on each other except during a collision.
• Pressure of Gas: According to kinetic theory, the pressure exerted by a gas is merely the momentum transferred to the walls of the container per second per unit area due to the continuous collisions of molecules of the gas. An expression for the pressure exerted by a gas can, therefore be obtained as follows: 
• Let a cubical vessel of side/, contains N molecules, each of mass m (Fig.11.1). The velocity v, of any one of these molecules can be resolved into three rectangular components Vix.Viy. Viz parallel to three co-ordinate axes x, y and z.
• Initial momentum of the molecule striking the face ABCDA is then mv. If the collision is assumed perfectly elastic, the molecule will rebound from the face ABCDA with the same speed. Thus each collision produces a change in momentum, which is equal to
• Final momentum - Initial momentum or change in momentum-mvxmV1x Change in momentum = -2 mv (11.1)
• After recoil the molecule travels to opposite face EFGHE and collides with it, rebounds and travels back to the face ABCDA after covering a distance 21. The time Af between two successive collisions with face ABCDA is 21 At=  (11.2). So the number of collisions per second that the molecule will make with this face is V 21. Thus the rate of change of momentum of the molecule due
• Definition of the pressure of the gas with the formula
• Relation to the pressure of the gas
• Interpretation of temperature with formula
• Derivation of gas law, Boyle's law, and Charle's Law
• Definition of internal energy
• Work and Heat and First Law of Thermodynamics with explanation
• Important 1st year physics chapter 11 solved exercise from Punjab Textbook.
• Iso Thermal Process with explanation
• Diabatic Process with explanation
• Adiabatic Compression with examples
• Molar Specific Heats of a gas
• Molar-specific heat at constant pressure
• Types of molar specific heat of a gas  and molar specific heat at constant volume
• Important 1st year physics chapter 11 important long questions from Punjab Textbook.
• Definition of reversible and Irreversible process at constant volume/ at constant pressure
• Definition of a cycle with examples 
• Definition of a heat engine with its principle
• State and prove carnot engine and Carnot's theorem
• The thermodynamic scale of temperature
• Important 1st year physics chapter 11 long questions from Punjab Textbook.
• Definition of the petrol engine
• Definition and explanation of Entropy
• The second law of thermodynamics in terms of Entropy
• Questions and their Solutions to the Exercises
• Important 1st year physics chapter 11 numericals from Punjab Textbook.