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An electric current through a conductor will produce a magnetic field at right angles to the direction of electron flow. If that conductor is wrapped into a coil shape, the magnetic field produced will be oriented along the length of the coil. The greater the current, the greater the strength of the magnetic field, all other factors being equal: Inductors react against changes in current because of the energy stored in this magnetic field. When we construct a transformer from two inductor coils around a common iron core, we use this field to transfer energy from one coil to the other. However, there are simpler and more direct uses for electromagnetic fields than the applications we’ve seen with inductors and transformers. The magnetic field produced by a coil of current-carrying wire can be used to exert a mechanical force on any magnetic object, just as we can use a permanent magnet to attract magnetic objects, except that this magnet (formed by the coil) can be turned on or off b...

Liquid Crystal Display (LCD) LCD are passive display devices characteristics by very low power consumption and good contrast ratio. The liquid crystal display does not emit light or generate light. It requires an external or internal light source. Although LED give off light but LCD are not light sources but controls light. LCD a reflect part of surround by light. Principle The molecules in ordinary liquids normally have random orientations. In liquid crystals, the molecules are oriented in liquid crystals, the molecules are oriented in a definite crystal pattern when an electric field is applied to these crystals the molecules which are approximately cigar shaped, tend to aligns themselves perpendicular to the field. Charge carriers flowing through the liquid disturb the molecular alignment and cause a turbulence within the liquid, this is illustrated in below fig .                                   ...