Capacitor

Capacitor:

A capacitor is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.

Dielectric:

A basic capacitor is made up of two conductors separated by an insulator, or dielectric. The dielectric can be made of paper, plastic, mica, ceramic, glass, a vacuum or nearly any other non conductive material. Some capacitors are called electrolytic, meaning that their dielectric is made up of a thin layer of oxide formed on an aluminum or tantalum foil conductor.

Cautions:

Capacitors may retain charge long after power is removed from a circuit; this ascribe can origin unsafe or even potentially mortal alarms or damage attached gear. For example, even an apparently innocuous apparatus such as a disposable camera flash unit driven by a 1.5 volt AA electric battery contains a capacitor which may be ascribed to over 300 volts. This is effortlessly adept of delivering a shock.

Photo Cell

Photo Cell:

It is a device for measuring or detecting light or other electromagnetic radiation, since its electrical state is altered by the effect of light.

Construction:

It is constructed up of a lamp box containing bulb, a micro ammeter, a photocell and a ruler to measure the distance between the lamp box and the micro ammeter.

Working:

When we switch on the bulb the rays of light emitted from the bulb goes out and strikes the photocell which shows some deflection on the micro ammeter. We note down the current and the distance in order to study the ratio of current striking the photocell.

In this experiment we use two bulbs, one is of 60 w and the other is of 100 w. We observe the two distances in order to calculate the average so that our result can be accurate.

Semiconductor Diode

Semiconductor Diode:

The most common kind of diode in modern circuit design is the semiconductor diode, although other diode technologies exist. The semiconductor diode is cut from a single crystal of a semiconductor material (such as silicon or germanium) to which special impurities has been added during manufacture so that the crystal is now composed of two distinct regions. One region contains semiconductor material of the p-type, which contains more positive charge carriers than negative; the other contains material of the n-type, which has more negative charge carriers than positive. The region of contact between the two types is called the p–n junction (depletion layer), and it is this that acts as the barrier preventing current from flowing.

The semiconductor diode has the valuable property that electrons only flow in one direction across it and as a result it acts as a rectifier. As it has two electrodes it receives its name - diode. In view of this, it is one of the most fundamental structures in semiconductor technology. The bipolar junction transistor, junction FET and many more all rely on the PN junction for their operation. This makes the semiconductor PN junction diode one of the key enablers in today's electronics technology.