The Science

Current electricity and ohm's law(Current electricity) :- •What is current? Rate of flow of electric charge with time through any cross section of a wire is called current. It is denoted by I . Thus if charge "dq" flows through a wire in small time "dt" then electric current through wire is given by :                                             I=dq/dt  1 ampere = 1coulomb/1 second  1A=C/s •Ampere :-                                                           The current Through a wire is called one ampere if one coulomb charge is flow through Any cross section of wire in one second   •Ohm's law:- Ohm’s principal discovery was that the amount of electric current through a metal conductor...

Reflection of light (Optics)  :-   •Reflection :- The phenomenon in which the light traveling in a medium ,when made incident on the surface of another medium goes back in the same medium is called reflection . •Law of reflection :- The following experiments observation are called laws of reflection.  1. The incident ray, the normal to reflecting surface at the point of incident and reflected ray all lie in same plane.  2. The angle of incidence(i) is always equal to angle of reflection (r).               i=r •Some definitions:- • Incident Ray:- The incident light ray is a narrow light beam which is represented by a straight line, it intersects with the reflecting surface at the point of incidence. • Reflected Ray:- The reflected light ray is a narrow light beam which is represented by a straight line that is reflected from the reflected surface at the point of incidence. ...

Electromagnetic waves :- An electromagnetic wave is one in  which electric and magnetic field mutually perpendicular to each other as well as the direction of propagation of the wave. An accelerated charge produces a sinusoidal time varying magnetic field, which in turm produces a sinusoidal time electric field. The two fields so produced are mutually perpendicular and are source of each  other. The mutually perpendicular time using electric field and magnetic field constitute a electromagnetic waves which propagate in space in direction perpendicular to the direction of both the fields. Thus the electromagnetic waves consist of sinusoidal time varying electric and -ve field acting at right angle to each other as well as at right angle to the direction of propagation of waves as shown in figure. • Characterstics of electromagnetic waves :- 1. The electromagnetic waves are produced by an accelerated charge.  2.At any point in vacuum, the electric fiel...

Alternating current generator   (Electromagnetic induction and current) :- The device which converts mechanical energy into electrical energy is called alternating current generator.  • Principal :-  When magnetic flux linked with a coil changes, an induced e m f is produced across it.  • Construction :- It is consist of following four parts.  1.Armature :-  Armature ABCD ( also called coil)  consist of a large number of turns of insulate copper wire around over a soft iron core. It revolves round an axle between the two poles of a strong magnet . 2. field Magnet :-  It is usually a strong permanent magnet. The armature is rotated between the two poles of a strong magnet so that axis of the armature is perpendicular to magnetic field lines . 3. Slip rings :--- The leads from the arms of the armature are connected to the two rings R1 and R2  Respectively. These rings help to provide...