Significant Figures
Whenever physical quantities are measured, two things must be borne in mind. First, it must be expressed in appropriate units such as CGS, FPS or S.I. The second important point is that the measu... |  |
 | Accuracy And Precision
When a product is manufactured, one must see that it serves the intended purpose. Unless a product is manufactured to the desired degree of accuracy and precision, it may not serve the purpose for wh... |
Atmospheric Pressure
Pressure is the force per unit area which is expressed as kg.f / m2. In S.I units it is expressed as N.m-2 which is called pascal. There is another unit for pressure which meteorologists, who study ... |  |
 | Centripetal Force
If the centripetal force is not present, the body cannot undergo uniform circular motion. Both centripetal acceleration and centripetal force are vector quantities whose magnitudes are constant but w... |
Acceleration Due To Gravity
According to Newton’s law, two masses, situated anywhere in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the... |  |
 | The Shell Theorem
“The gravitational force on a mass placed anywhere inside a shell is zero”. Suppose, our planet earth is a hollow sphere instead of a solid sphere, a person does not experience ... |
How Atoms Combine To Form Matter
Anything that occupies space and has mass is called matter. Everything we see around is made up of different kinds of matter. The fundamental building blocks of matter are known as atoms. An atom is ... |  |
 | Latent Heat
Latent heat means the heat that is hidden or latent which is not observable just by measuring the temperature of the substance. Remember heat is a form of energy. For example, consider the ice at 00C... |
Wave Motion
All electromagnetic radiations including light and sound travel from one place to the other in the form of waves. Therefore, study of the wave phenomenon is very important in understanding the ... |  |
 | Electrical Resistance
Suppose there is a conductor through which one-ampere of current is flowing. This means a charge of one coulomb is moving every second. But a flow of charge is same as the nu... |
Theory of Magnetism
More than 2000 years ago, some iron ore, known as magnetite, was discovered. It was observed that this ore is getting attracted to a stick fitted with an iron cap.
Later,... |  |
 | Angle of Dip and Declination
In a limited space, it can be assumed that the lines of force due to Earth's magnetic field are parallel and equidistant. When a bar magnet is suspended freely it aligns along the Earth's magnetic ... |
Solenoid
A solenoid is an electromagnet that is made by winding of a conducting wire, in the form of loops, over a magnetic material. When a current is passed through the wire, the core material becomes a p... |  |
 | Color code for Resistance
Resistors are used in electrical or electronic circuits; only resistors of appropriate values have to be used according to the design of the circuit. In order to identify the value of a resistor, a... |
A C.generator
An electric generator works on the laws of electromagnetic induction discovered by Faraday. The principle is opposite to the working of a electric motor. When there is change in the magnetic flux p... |  |
 | D C.Motor
One can see motors working in many appliances used in our homes and industry. For example, a tape-recorder, kitchen grinder, water-pump, computer drives, etc, use either an a.c motor or a d.c motor... |
Speed of Sound
Sound propagation comprises of longitudinal waves with compressions and rarefactions. The particles of the medium vibrate in the direction of propagation. The speed of sound is different for differ... |  |
 | Echo of Sound
Every one might have experienced the echo of his voice near a mountain range. When a person stands facing the mountain and shouts his name, the same thing is heard after few seconds when the sound ... |
Mass Defect and Binding Energy
An atom comprises of three types of particles known as protons, neutrons and electrons. The protons and neutrons are lodged in the nucleus at the center of the atom while the electrons revolve arou... |  |
 | Nuclear Fission
The discovery of neutron has encouraged many scientists around the world to do intense research to produce energy through nuclear fission reactions. When an uranium atom is bombarded with a slow mo... |
Nuclear fusion
Sun is providing us light and energy because of fusion reactions that are taking place inside the sun. A fusion reaction is a process that is opposite to the fission reaction. In fission reaction, ... |  |
 | Carbon Dating
The decay of a radioactive element and its complete independence of physical and chemical conditions give us an extremely valuable method for estimating the age-old geological formations and archeo... |
Radiation Hazards
The inevitable number of nuclear reactor installations for producing electrical power has focused public attention on the possible hazards of nuclear radiation, which can harm any living organism. ... |  |
 | Isotopes
A simple hydrogen atom comprises of a single proton in its nucleus with single electron revolving around the nucleus. As the number of protons in the nucleus increase, we get... |
Energy Sources
Sun is the energy source that nourishes life on earth, gives life to plants, which in turn become food for the animals, and through the difference in temperatures, over different regions on earth, ... |  |
 | Vacuum Diode
Before transistors came into existence vacuum diodes and triodes are extensively used in radios and other electrical and electronic equipment. A diode can be used as a valve for flow of current, an... |
Half-wave Rectifier
A semiconductor p-n junction has low resistance for one direction of applied voltage under forward bias, and high resistance under reverse bias. Since this behaviour is similar to a vacuum diode, i... |  |
 | Transistor
The transistor was invented by John Bardeen in 1948. The word "transistor" is the abbreviation for transference of signal across a resistor. If a p-n diode is formed by a crystal having t... |
Capillarity
The molecules on the surface of a liquid have more potential energy then the molecules below the surface. A molecule on the surface tries to acquire its natural spherical shape, but is prevented du... |  |
 | Buoyancy
It is know that a piece of wood will float on the surface of water while a piece of iron will sink to the bottom. Although a solid metal object will not be entirely supported by water and so will s... |
Inertia
According to the First Law of Newton, "Every object in this universe will continue in its state of rest or uniform motion in a straight line unless acted upon by some external force". |  |
 | Brownian Motion
Molecules of a liquid are so tiny, they cannot be observed even by using a microscope. However, one can understand that the molecules of a liquid are in random motion. It can be verified indirectly... |
Anamolous Expantion of water
Liquids expand on heating and contract on cooling. However, the thermal expansion is confined to its volume. So, one cannot observe any linear or superficial expansion in liquids on heating. This i... |  |
 | Dispersion of Light
The eye can see the objects around in their natural colours. However, it has taken centuries for scientists to develop optical instruments like colour camera and colour television. But for these de... |
Photographic Camera
Every one is familiar how a photograph of people or surrounding scenery is taken by a camera. The functioning of a camera is similar to the functioning of our eye. The eye is the most versatile opt... |  |
 | Electromagnetic Spectrum
The light we see coming from the sun, the X-rays doctors use to take picture of a fractured bone, the microwaves that are used for communication, the gamma rays emitted by uranium all belong to same ... |
Geiger Counter
A number of devices have been developed for tracking and photographing nuclear transformations. In the early experiments conducted by Rutherford, the scattered alpha particle is made to strike a tr... |  |
 | S.I.Units
Until the late 18th century, people used to communicate measurements of length to each other with the help of their body parts. For example, an 'inch' was the width of one's thumb, a 'foot' was the... |
Escape Velocity
According to the Newton's law of gravitation, any two masses would attract towards each other. This gravitational force extends to infinity. A great deal had been written about escape velocity ever... |  |
 | Radius of Gyration
All bodies exhibit resistance to rotational motion just as in the case of linear motion. For example, it is very difficult to rotate a flywheel that is heavy compared to the one that is lighter. <... |
Bohrs model
Rutherford first evolved the model of a simple hydrogen atom in the beginning ogf the 20th century. However, this could not explain properly the distribution of electrons around the nucleus of atom... |  |
 | Semiconductor
Materials, for electronics applications, are classified into three groops: Metal conductors, semiconductors and insulators. These properties depend on the electron configuration of each material. T... |
Photoelectric cells
The phenomenon of emission of electrons from a surface and flow of electric current under the action of photons of light is known as photoelectric effect. However, the photoelectric phenomenon coul... |  |
 | Heat and Temperature
Heat is a form of energy since it can do work. Steam engine, internal combustion engines, gas turbines are examples of heat engines. Heat flows from a body at a higher temperature to body at a lowe... |
Semiconductor diode
In a silicon atom, four valence electrons are engaged in forming a covalent bond. At low temperatures, these bonds are not broken. As explained earlier, silicon is a semiconductor which means it ha... |  |
 | Complimentry colors
Every one likes colours. Nature is full of colours. We can see colours because the reflected light from the colourful objects falls on the retina of our eye and stimulates the rods and cones that c... |
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