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# Electric Circuits and Their Components Electric circuits act as a pathway for the electric current. They are the rightful conductor of current form one end to another. An electric circuit is designed so that they are the safest methods of sending electric current from one point to another. In the simplest form, an electric current consist of a bulb, a wire and a cell. All of these components are essential to completing the electric circuit. There are two types of circuits

o Closed Circuit: A closed circuit is the one in which the path of the current is continuous

o Open Circuit: The type of circuit in which the path of the current is not continuous is called an open circuit.

Cells:

Alessandro Volta discovered electric cells in 1800 when he realized that the path for a continuous current could be laid by putting layers of zinc and silver discs over one another. However, each of these discs needs to be separated from one another by a cloth or a paper that is dipped in NaCl solution. So in short, an electric cell is a chemical device that is used to continuously supply the electric current from one point of the circuit to another.

Resistors:

Resistors are a very important part of electronics in modern times. Resistors are electrical gadgets which control the current flow through a circuit, (the path through which electricity flows). There is a lowering in voltage (current) between two points. Resistors depend on something called Ohm’s Law, which you will learn about in later years. It is important that you remember at this stage that Resistors are based on the theory of Ohm’s Law.

Resistors are of five types. Here they are:

o Fixed Value Resistors

o Variable Resistors

o Potentiometers

o Thermistors

o Photo Resistors

Variable Resistors:

When a potentiometer has only two connecting wires in place of three it is called a variable resistor. You may refer to your notes on Resistors to know what a potentiometer is. The parts which make up are the same for both but they do very different jobs. The potentiometer would let you control the current that passes through a circuit. The variable resistance allows you to make adjustments between the two nodes on a circuit. The Potentiometers are also called pots.

Current

Electric current is defined as the flow or movement of electrons or electron-deficient atoms. It is represented by the upper case letter I and is measured in amperes represented by A. Current flows from relatively positive points to relatively negative points.

There are two kinds of electric current such as Alternate current (AC) and Direct current (DC). Alternate current is an electric current in which the flow of current changes direction and magnitude cyclically. On the other hand, direct current is the continuous flow of electric charge whose direction is not subject to change. Direct current was earlier referred to as Galvanic current.

Voltage

Voltage is known as the difference of electrical potential between two points of an electric circuit. It is also referred to as electric tension and is measured in volts. This unit is used to measure the potential of an electric field to make electric current flow through a conductor. Voltage is classified as low voltage, high voltage, extra low voltage and extra high voltage based on the difference of the electrical potential. Initially, voltage or potential difference was referred to as electromotive force (EMF).