Free notes of Some important laws and its statements of physics class 12th

1.  Laws:-

• Newton law of gravitation : Every planets of matter attract each other particles of matter with a force which directly proportional to the product of their masses and inversely proportional to the distance between them.

 

•  Kepler s laws:- 1) first law :- all planets revolves around the sun in elliptical orbit with the sun at one focus of the orbit.                                                                                          2) second law:- the radius vector drawn from the sun to the planet swept equal area in equal interval of time.                                                                                                                    3) third law:- the square of the period of revolution of the planet is directly proportional to the cube of the mean distance of the planet from the sun                                                                                                   
•    Law of the conservation of the angular momentum:- if their is the no external torque is applied to the rotating body then the total angular momentum of the body remain same or constant.                                     
•    Law of simple pendulum:- the period of simple pendulum is directly proportional to the square root of the length and inversely proportional to the gravitation acceleration of the earth .                                                            
•   Or simple pendulum time period is independent of the mass of the Bob,material of the Bob, amplitude of the motion thus the provided amplitude is small .                                                                        
•   Hookes law:- within the elastic limit the stress produce in body is directly proportional to the strain produce in the body.                                                                           
•    Doppler effect (for sound):- the appearant change in frequency of the sound due to relative motion between the source and the observer is called as Doppler effect.                 
•   Law of the vibrational strings :-  1/2l√T/M.                                                                                       1) law of the length :- the fundamental frequency of the vibration of the stretched string is inversely proportional to the length of the string if the tension in the string and mass per unit length of the string remain constant.                                                                                                 ..                                2) law of tension:- the fundamental frequency of vibration of starched string is directly proportional to the square of the square root of the tension in the string if the vibrational length of string and mass per unit length is remain constant.                                                                                                 3) law of the mass per unit length:- the fundamental frequency of the vibration of the stretched string is inversely proportional to the square root of the mass per unit length of the vibrating length and tension of the string remain constant.              
•    Boyles law  :- for the given mass of the gas of constant temperature of the gas and pressure exerted by the gas is inversely proportional to the volume of the gas in container.                                                                       
•   Charles law :- at the fixed pressure, the volume of the gas present in container is directly proportional to the absolute temperature of the gas.                                         
•   Dalton's law of partial pressure:- the total pressure of mix ideal gases is the sum of the partial pressure.                                                    
•  Law of equipartition of energy :- for any dynamical system in thermal equilibrium, the total energy is equally distributed to amongst all degree of freedom and the energy associated with each molecule per degree of freedom is 1/2 kb *T.     Where Kb is the bolzman constant and T is the temperature .                                                          
•  Weins displacement law :- the product of the wavelength corresponding to the maximum value of the wavelength and absolutely temperature of black body is constant .                                                                
•  Krichoffs law :- the coefficient of the absolute of the body is equal to the its coefficient of the emission at given to temperature.                                                           
•   Stefan's law of the radiation's :- the emission power of the perfectly black body is directly proportional to the fourth power of the its absolutely temperature.                       
•   Newton's law of cooling :- the rate of the loss of heat by a body is directly proportional to the excess temperature of the body over the surrounding provided the excess temperature is small.                                
•  Zeroth law of thermodynamics :- if two body P and Q are in the thermal equilibrium and also P and R in thermal equilibrium then Q and R are in the thermal equilibrium .                                           
•  First law of the thermodynamic:- the energy supplied to the system goes in partially to the increase the internal energy of the system and the rest in work on environment.                                                         
•  Second law of thermodynamics:- mechanical work can be converted to completely into the heat but heat cannot be converted into mechanical work i.e work and heat are not equivalent.                                 
•   Third law of thermodynamics   :- it is stated that the entropy of the system is constant or zero and at that temperature is zero .

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