EMITTER, COLLECTOR AND BASE OF A TRANSISTOR

A transistor has three sections, The section on one side is Emitter, and the section on the opposite side is the collector.  The middle section is called the base.

Emitter:
The section on one side that supplies charge carriers (electrons) is called the emitter. The emitter is always forward biased with respect to base.

Collector:
The section on the other side that collects the charges is called the collector. the collector is always reverse biased.  Its function is to remove charges from its junction with base.

Base:
The middle section which forms two pn junctions between the emitter and collector is called the base.
The base emitter junction is forward biased and the base-collector junction is reverse biased.

TRASISTOR

When a third doped element is added to a crystal diode in such a way that two pin junctions are formed, the resulting device is known as transistor.

A transistor consists of two pn junctions formed by
sandwiching either p type or n type semiconductor between a pair of opposite types.

there are two types of transistors

1) n-p-n transistor
2) p-n-p transistor


A n-p-n transistor is composed of two n-type semiconductors separated by a thin section of p-type semiconductor. 

A p-n-p transistor is composed of  two p-type semiconductors separated by a thin section of n-type semi conductor.

In any transistor, there are two pn junctions.  therefore a transistor may be regarded as a combination of two diodes connected back to back.

There are three terminals in a transistor  1) Emitter
2)Collector    3) Base

WHAT IS A COLUMN, SHORT COLUMN, LONG COLUMN

Column:
A column is a vertical compression member.  A column is subjected to axial compressive loads.

Short Column:
When the ratio of effective length to the least lateral dimensions of the column is less than 12, then it is
called a short column.

(or)
When the ratio of effective length to the least radius of gyration is less than 45, then it is called a short column

Long Column:
When the ratio of effective length to the least radius of gyration is greater than 45, then it is called a long column.

A long column is subjected to bending moment in addition to direct compressive stress.

The load carrying capacity of a long column is less than a short column

The load carrying capacity of a long column depends upon slenderness ratio (slenderness ratio increases then the capacity of the column decreases)

WHAT IS FOREX, FOREIGN EXCHANGE MARKET

Foreign Exchange, simply called Forex
also called as currency market.  Simultaneous purchase and sale of one country's currency to
another country's currency.  in simple terms
buying of one currency and selling another currency at the same time.

The world currencies do not have a fixed exchange rates and they are always fluctuating.

Forex trading allows an investor to participate in profitable fluctuations of world currencies.