Physics Notes – Important Definitions and Laws – Static Science GK Material for Competitive exams

Important Definitions and Laws

⦁ CAPILLARITY – When a capillary tube is dipped in a liquid, liquid ascends or descends in a capillary tube. This phenomenon is called capillarity.
⦁ VISCOSITY – The property of a liquid by virtue of which it opposes the relative motion between its different layers is called viscosity.
⦁ ELASTICITY – The property of material of a body by virtue of which a body acquires its original shape and size after the removal of deforming force applied on it is called elasticity.
⦁ STRESS – The restoring force per unit area inside the body which is subjected to deforming force is called stress.
⦁ STRAIN – The relative change in dimension or shape of a body which is subjected to stress is called strain.
⦁ PERIODIC MOTION – The motion which repeats itself after regular interval of time is called periodic  motion.
⦁ OSCILLATORY MOTION – If a particle repeats its motion after a regular interval of time about a fixed point, the the motion is said to be oscillatory motion.
⦁ TIME PERIOD – Time taken by a body in one complete oscillation is called time period or the time after which motion is repeated is called time period.
⦁ WAVE – A wave is a disturbance which propagates energy from one place to other without the transport of matter.
⦁ LONGITUDINAL WAVE – In a longitudinal wave, the particles of the medium vibrate in the direction of propagation of wave.
⦁ TRANSVERSE WAVE – In a transverse wave the particles of the medium vibrate perpendicular to the direction of propagation of wave.
⦁ AMPLITUDE –  The maximum displacement of the vibrating particle on the either side from the equilibrium position is amplitude.
⦁ WAVE LENGTH – Wavelength is the length between two nearest particle of the medium, vibrating in the same phase. It is denoted by the Greek letter lambda.
⦁ AUDIBLE WAVES – The longitudinal mechanical waves which lie in the frequency range 20 Hz to 20000 Hz are called audible or sound waves.
⦁ INFRASONIC WAVES – The longitudinal mechanical waves having frequencies less than 20 Hz are called infrasonic waves.
⦁ ULTRASONIC WAVES – The longitudinal mechanical waves having frequencies greater than 20000 Hz are called ultrasonic waves.
⦁ Bat can detect and produce ultrasonic sound.
⦁ Speed of sound is maximum in solids and minimum in gases.
⦁ When sound enters from one medium to another medium, its speed and wavelength changes but frequency remains unchanged.
⦁ STATIONARY WAVE – When two progressive waves of same type having the same amplitude and same time period/frequency/wavelength travelling with same speed along the same straight line in opposite directions, superimpose, a new set of waves are formed which are called stationary of standing waves.
⦁ TEMPERATURE – Temperature decides the direction of flow of heat from one body to other body. Heat energy always flows from body at higher temperature to body at lower temperature.
⦁ SPECIFIC HEAT CAPACITY – Specific heat capacity of a material is amount of heat required to raise the temperature of unit mass of substance through 1 degree Celsius.
⦁ TRANSMISSION OF HEAT – The transfer of heat from one place to other place is called transmission of heat. There are three modes of heat transfer- Conduction, Convection and Radiation
⦁ CONDUCTION – In this process, heat is transferred from one body to other by successive vibrations of the particles of the medium without bodily movement of the particles of the medium. In solids, heat transfer takes place by conduction.
⦁ CONVECTION – In this process, heat is transferred by the actual movement of the particles of the movement from one place to other place. Due to movement of particles, a current of particles set up which is called convection current.
⦁ RADIATION – In this method transfer of heat takes place with the speed of light without affecting the intervening medium.
⦁ NEWTON’S LAW OF COOLING – The rate of loss of heat by a body is directly proportional to the difference in temperature between the body and the surrounding.

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