Magnetism

Magnetism - Magnetism is a force of attraction or replusion that acts at a distance. It is due to a magnetic field, which is caused by moving electrically charged particles or is inherent in magnetic objects such as a magnet.

Magnetism - A magnet is an object that exhibits a strong magnetic field and will attract materials like iron to it. Magnets have two poles, called the north (N) and south (S) poles. Two magnets will be attacted by their opposite poles, and each will repel the like pole of the other magnet. Magnetism has many uses in modern life.

Current Electricity

Electric Current - The Electric current is a flow of electric charge through a conductive medium.

In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in a plasma.

The SI unit for measuring the rate of flow of electric charge is the ampere, which is charge flowing through some surface at the rate of one coulomb per second. Electric current is measured using an ammeter.

Static Electricity

Static electricity is an excess of electric charge trapped on the surface of an object. The charge remains until it is allowed to escape to an object with a weaker or opposite electrical charge, such as the ground, by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy.

Light

Light is a type of energy which propagates as electromagnetic waves. In the spectrum of electromagnetic waves, light has place between ultraviolet and infrared region.

Some Facts About Light

•    Electromagnetic waves are transverse waves, therefore, light is also transverse wave.
•    Wave nature of light explains; rectilinear propagation of light, reflection of light, refraction of light, interference of light, diffraction of light and polarization of light.
•    The happenings in physics like Photoelectric Effect and Compton Effect can not be explained on the basis of wave nature of light. These phenomenons are explained on the basis of quantum theory of light, explained by Albert Einstein.
•    The quantum theory of light, considers light as a packet or bundle of energy, these energy packets are called photons. Photon associates with it as Energy E; where E = hv
•    Light has dual nature and behaves as a particle as well as wave.
•    Speed of Light was first calculated by Roemer in 1678 AD.
•    Speed of light is maximum in vacuum, which is equivalent to 3x108 m/s.

Thermodynamics

First Law of Thermodynamics

The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes:

The change in internal energy of a system is equal to the heat added to the system minus the work done by the system.

Mathematically, ΔU (Change in Internal Energy) = Q (Heat added to or drawn from the system) – W (Work done by the system)

Heat

Heat may be defined as energy in transit from a high temperature object to a lower temperature object.

Some Characteristics of Heat and Mathematical Equivalent

•    Heat is also defined as the transfer of kinetic energy from one medium or object to another, or from an energy source to a medium or object.

•    The heat transfer can occur in three ways: radiation, conduction, and convection.

•    The standard unit of heat in the International System of Units (SI) is the calorie (cal).

•    One calorie is defined as the amount of energy transfer required to raise the temperature of one gram of pure liquid water by one degree Celsius, provided the water temperature is higher than the freezing point and lower than the boiling point.

•    Sometimes the kilocalorie (kcal) is specified as a unit of heat; 1 kcal = 1000 cal. This is the also called diet calorie.

•    The amount of heat contained in a body depends upon the mass of the body.

•    If W is work performed and Heat produced is H, then W/H = J or W = JH, where J is a constant called mechanical equivalent of heat. The value of J is 4.186 Joule / Calorie. This means if 4.186 Joule of work is done, 1 Calorie of heat is consumed.

Sound Waves

•    Sound is a mechanical wave that results from the back and forth vibration of the particles of the medium through which the sound wave is moving.
•    If a sound wave is moving from left to right through air, then particles of air will be displaced both rightward and leftward as the energy of the sound wave passes through it.
•    The motion of the particles is parallel (and anti-parallel) to the direction of the energy transport. This is what characterizes sound waves in air as longitudinal waves.
•    The mechanical vibrations which can be said as sound are able to travel through all forms of matter i.e. solids, liquids and gases. The matter which allows the sound to travel through it is called the medium.
•    Sound cannot travel through a vacuum.