Reflection of light

Reflection of light    Light moving in one medium when falls at to surface of another medium, part of light returns back to the same medium. This phenomenon of returning back of the light in the same media is know as reflection of light.    Reflection of light from plane mirror  Before understanding the laws of reflection of light, lets understand the meaning of some important terms such as, inciden Read More


Polarisation   Polarisation is the orientation of vibration perpendicular to the direction of energy travel.  Plane polarisation is the method of allowing only waves orientated in the same direction - only allowing vibrations in one plane. Only transverse waves can be plane polarised because their vibration is perpendicular to the direction of energy travel - you can therefore have this vibration at different orientat Read More

Bernoulli's Principle

Bernoulli's Principle   This is an important principle involving the movement of a fluid through a pressure difference. Suppose a fluid is moving in a horizontal direction and encounters a pressure difference. This pressure difference will result in a net force, which by Newton's 2nd law will cause an acceleration of the fluid. The fundamental relation, in this situation can be written as which furthermor Read More

Viscosity of liquids

Viscosity of liquids When we move our fingers through any liquid we experience a resistance. This is because liquid offers a frictional force.   The resistance offered by fluids (liquids as well as gases) to relative motion between its different layers is called viscous force. This property is called viscosity.   The viscous forces are similar to frictional forces which resist relative motion between two Read More

Atmospheric Pressure

Atmospheric Pressure At sea level the Earth's atmosphere is pushing on you from all sides with a pressure of 101,000 N/m2 (101 kPa). As you climb higher - away from sea level - that pressure decreases. This is because there is less air above you, weighing you down. We are not aware of the air pressure - we are designed to live with it. If we go to high altitudes we have difficulty breathing. This is because our lungs are used to ta Read More

The Atmosphere

The Atmosphere The Earth's atmosphere is a layer of gases surrounding the planet Earth that is held in place by the pull of Earth's gravity. We call our atmosphere 'the air'. The atmosphere is held onto by planet Earth by the pull of gravity. Planets and moons with a weaker gravitational field than Earth's have thinner or even no atmospheres. The gases just escape into space.  We are lucky that our planet h Read More

Depletion of Ozone Layer

Depletion of Ozone Layer The Earth's ozone layer protects all life from the sun's harmful ultraviolet radiation (UVB), but human activities have damaged this shield. Less protection from ultraviolet light will, over time, lead to higher skin cancer and cataract rates and crop damage. The Earth's atmosphere is divided into several layers.The lowest region, the troposphere, extends from the Earth's surface up to about 10 Read More


IMPORTANT ELEMENTS AND TERMS OF PHYSICS   Acceleration: It is the rate of change of the velocity of a moving body. Acoustics: It is the experimental and theoretical science of sound and its transmission. Alternative energy: It is the energy from sources that are renewable and ecological safe, as opposed to sources that are non-renewable with toxic by-product, such as coal, oil or gas and uranium. Altimeter: It is an in Read More

Thrust and pressure

Thrust and pressure :-   Thrust : Thrust is the force acting on an object perpendicular to the surface.   Eg :- When you stand on loose sand the force (weight) of your body is acting on an area equal to the area of your feet. When you lie down, the same force acts on an area equal to the contact area of the whole body. In both cases the force acting on the sand (thrust) is the same.   Pressure Pressure is Read More


Gravitation 1) Gravitation :  Gravitation is the force of attraction between two objects in the universe.  i) Gravitation may be the attraction of objects by the earth.     Eg :- If a body is dropped from a certain height, it falls downwards due to earth’s gravity.  If a body is thrown upwards, it reaches a certain height and then falls downwards due to the earth’s gravity. ii) Grav Read More

Atomic and Nuclear Physics

Atomic and Nuclear Physics Cathode Rays  Cathode rays, discovered by Sir William Crooke and its properties are  • travel in straight lines • Produce fluorescence • can penetrate through thin foils of metal and deflected by both electric and magnetic fields. • have velocity ranging 1/30th to 1/10th of the velocity of light.   Positive or Canal Rays  • These rays we Read More

Thermal Expansion

THERMAL EXPANSION : The expansion of a body caused by heat is known as thermal expansion   THERMAL EXPANSION OF SOLIDS Thermal expansion of solids is of three types 1) Expansion in length on heating is called Linear Expansion. The increase in length of a rod of unit length of a substance due increase in its temperature by 1'C is called the Coefficient of Linear Expansion of the substance of that rod. It is represen Read More


TEMPERATURE : Temperature is the measure of hotness or coldness of a body The heat flows from one body to another due to the difference in their body temperature   SCALE OF TEMPERATURE  To measure the temperature of a body following temperature scales are used Celsius Scale of temperature ice point is 0' C. Boiling point of water  = 100'C Fahrenheit Scale of temperature ice point = 32'F . Read More

Atomic Energy

ATOMIC ENERGY  It is the energy produced by atoms. It is also referred as nuclear energy. It is created during nuclear reactions. It is obtained by the following process : Nuclear Fission  and Nuclear Fusion   NUCLEAR FISSION It is the process in which a heavy nucleus is broken down into two or more medium heavy fragments. It is used in nuclear reactor and atom bomb   NUCLEAR FUSION The proce Read More


FORCE : It is an external push or pull which can change or tries to change the state of rest or Uniform motion. SI unit is newton (N) and CGS unit is Dyne. 1 N = 105 dyne If sum of all the forces acting on a body is zero, then body is said to be in equilibrium In nature, there are four basic types of forces Gravitational force                     Electromagnetic force We Read More


SCATTERING OF LIGHT : When light passes through a medium in which particles are suspended whose sizes are of the order of wavelength of light, then on striking these particles, deviated in different direction. This phenomenon is called Scattering of Light. Therefore,RED color of light is scattered least (Wavelength is highest) and VIOLET color of light is scattered most (Wavelength is least) Danger Signals are of red color because red Read More


WAVE -- A wave is a vibratory disturbance in a medium which carries energy from one point to another point without any actual movement of the medium. TPYES OF WAVES Mechanical Waves-- Those waves which require a material medium for their propagation. For examples -- Sound waves, water waves etc Electromagnetic Waves - Waves which do not require a material medium for their propagation. For example  Light waves, Radi Read More

Kepler's Law of Planetary Motion

Kepler's Law of Planetary Motion : Kepler's Three laws are 1) All Planets revolve around the sun in elliptical orbits with the sun at its one focus. 2) The areal speed of a planet around the sun is constant 3) the square of the time period (T) of revolution of a planet around the sun is directly proportional to the cube of the semi major axis of tis elliptical orbiti.e    T2 is directly proportional to a3 Read More

Scientific Explanations of Common Phenomena

SCIENTIFIC EXPLANATIONS OF COMMON PHENOMENA : 1) It is dangerous to sleep in an unventilated room with fire burning inside because the fire produces Carbon Monoxide and Carbon Dioxide gases. Both gases are poisonous and can cause death.   2) Ice wrapped in a blanket does not melt away quickly because woollen blanket is a bad conductor of heat.   3) White roof keeps the house cooler in summer than black roof becaus Read More


1)  Archimedes Principle : When a body is immersed either wholly or partially in a fluid at rest, the apparent loss of weight suffered by it is equal to the weight of the fluid displaced by it 2) Doppler's Principle : When the distance between the source of a wave and the observer increases due to their relative motion, the frequency of the wave appears to decrease. The converse condition is also true. 3)  Avogadr Read More

Surface Tension with Examples

SURFACE TENSION ---   Surface tension is the elastic tendency of liquids that makes them acquire the minimum surface area. It has the dimension of force per unit length, or of energy per unit area . If F is the force acting on length I then surface tension: T = F/L SI unit is Newton/m  and Dimensional formula MLT-2     ADHESION AND COHESION ------   Cohesion--- water stick to itself or f Read More

Units of Physics

FUNDAMENTAL PHYSICS UNITS (7 funademental basic units) QUANTITY UNIT Length Metre Mass Kilogram Time Second Temperature Kelvin Electric Current Ampere Luminous Intensity Candela Amount of Substance Mole   Read More

Newton First Law

A pull or push is called force. Example – to open a door, either we push or pull it. Or by applying brakes, a running cycle or a running vehicle can be stopped.   Effect of Force:   Force can make a stationary body in motion, can stop a moving body, can change the direction of a moving object, can change the speed of a moving body,can change the shape and size of an object.   Few examples are given Read More

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