Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction
The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage
Chapter 7 Atomic Structure (Class XII)
Atomic Structure. An atom is a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus.
This nucleus contains most of the atom's mass and is composed of protons and neutrons (except for common hydrogen which has only one proton),
Chapter 2 Electric Current (Class XII)
An electric current is a flow of electric charge. 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 an ionised gas (plasma)
Electrostatics is a branch of physics that deals with study of the electric charges at rest. ...
Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulomb's law.
The SI unit of capacitance is the farad (symbol: F), named after the English physicist Michael Faraday.
A 1 farad capacitor, when charged with 1 coulomb of electrical charge, has a potential difference of 1 volt between its plates.
The reciprocal of capacitance is called elastance.
Chapter 4 Electromagnetic Induction (ClassXII)
Current produced by the relative motion of coil or magnet is called induced current, set up by an induced electromotive force or EMF.
The production of EMF in a coil is called the phenomenon of ELECTROMAGNETIC INDUCTION
Chapter 3 Magnetic Field (Class XII)
Magnetic fields are produced by electric currents, which can be macroscopic currents in wires, or microscopic currents associated with electrons in atomic orbits
The magnetic field B is defined in terms of force on moving charge in the Lorentz force law.
Chapter 6 Optics + Wave optics (Class XII)
Optics is the branch of physics which involves the behaviour and properties of light,
including its interactions with matter and the construction of instruments that use or detect it.
Optics usually describes the behaviour of visible, ultraviolet, and infrared light.
In physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid.