Electric circuit and Electrical Symbols

Introduction

Electric circuit and electrical symbols are important to understand to design any electrical or electronic instrument. The branch of physics that deals with the behavior of electrons using electronic circuits are called electronics. The components used in the electronic circuits are active devices and this is the difference between classical electrical engineering and electronics. Electronics has many branches. Vacuum tubes play a vital role in the electronics field.

It is the first and basic of electronics that is used to control the movement of electrons. Then IBM transistors take the place of vacuum tubes. Due to some disadvantages of earlier transistors, IBM is used in many electronic applications. Due to the many advantageous factors of the MOSFET transistor, it makes a revolution in the electric field. If the components of the circuit are large then the connecting wires also need to be high and the current flow time also increased. This is overcome by an integrated circuit.

What is an electric circuit?

The flow of electricity from one point to another point through a closed path is called a circuit. Electric current passes through a closed path. They use many electrical components such as a transistor, resistor, capacitors, etc. Computers like many electronic devices are composed of these electronic components which are constructed by thousands of electric circuits.

Types of electric circuit

There are five different types of electric circuits and they are open circuit, close circuit, short circuit, series, and parallel circuit.

• Open circuit − There is a current flow in the circuit only if the circuit is a closed path or the power source should be in the on mode. If the switch is off or there is a break in the circuit it means it is called an open circuit.

• Closed-circuit − If there is current flow in the circuit without any interruption then it is called a closed circuit.

• Short circuit − If the two terminals or two polarities of the power source are connected then this condition is called a short circuit. The current flow under this condition is high.

• Series circuit − In a series circuit two or more loads are connected in series. The current through the circuit in only one path. The disadvantage of the series circuit is if the circuit breaks then every load loses its supply.

• Parallel circuit − In a parallel circuit two or more loads are connected in parallel. The current flows in different paths. If there is a break in the circuit the consequent load only cuts off. But current passes through other loads.

A short history of circuits and systems

The invention of the battery is the first development in the electric circuit. Static electricity is the flow of transfer of electrons by friction. There is no continuous flow of current. But the invention of the battery overcomes this. The battery produces a continuous flow of current. The first battery was invented by Alessandro Volta in 1800. The first electric circuit is made of batteries and electrodes immersed in water. The first application of electric circuits is electric lighting. In a short time after the invention of the battery, Thomas Edison invented the first incandescent light bulb and it was applied first in the United States. Due to this DC, only a small area is illuminated due to the loss in the wire. Then the alternating current is introduced. With the help of AC and transformers, long-distance power transmission is made possible. Further, it gets improved with to use of integrated circuits.

Components of an electric circuit

The basic circuit components that are used in electric circuits are the power source, switch, bulb, and connecting wire.

Power source

The source for a basic circuit may be a battery, photocell, or a thermocouple which used to give the current supply. There are two terminals in the power source positive and negative terminals. This polarity must be taken into consideration to avoid equipment damage.

Switch

The switch is an electric device that is used to open or close the circuit. If the switch is open there is no flow of current through the circuit. If the switch is closed there is a flow of current through the circuit. It is also called a key.

Bulb

In a light bulb, there is a filament made up of tungsten. When current passes through the filament it emits light. The electrical energy given to the light bulb is converted into light energy.

Connecting wire

Connecting wires are made up of conductors that are used for the transmission of current through the circuit.

List of electrical components with symbols

There are many components in electronic circuits. The symbols used for those electronic components are given below. In this way, only the components are represented in a circuit diagram.

• Resistor − It is a component in a circuit that resists the flow of current in the circuit. The unit of a resistor is Ω. A variable resistor is used to adjust the resistance value. A rheostat is a variable resistor having three terminals that are used to adjust voltage dividing. If the resistance depends on temperature, then it is known as a thermistor. If the resistance depends upon the luminosity, then it is known as a light-dependent resistor (LDR).

• Capacitor − Capacitors store electrical energy in the electric field. If the capacitance of the capacitor changes mechanically or electronically then it is called a variable capacitor. In a polarized capacitor, anodization forms an oxide layer in the anode.

• Power source − A power source is a device that gives electric power to the circuit.

• Inductor − It is an electronic component that stores energy in the magnetic field and electric field that flows through it.

• Transistor − There are two types of transistors and they are NPN transistors and PNP transistors. In NPN transistors P-type semiconductor is fused between two N-type semiconductors. In a PNP transistor, an N-type semiconductor is fused between two P-type semiconductors. Their symbols are given below.

• Diode − A diode is a two-terminal semiconductor device that allows the flow of current in one direction. In a Zener diode, the flow of current reverses when it reaches a certain point called Zener voltage. Photodiode converts light into electrical energy.

• Logic gates − There are three basic gates OR, AND, and NOT gate. NAND gate and NOR gate are the inverse operations of AND and OR gate. Their symbols are given below.

• Wires − The straight lines in the circuits represent the wire. It is used for connecting the components in the circuit. Below symbols are used for wire. interconnecting wire and wire crossing without joint.

• Switch − The switches are used to keep the circuit ON or OFF. The symbol for the switch is given below.

• Ground − The symbols used for grounding are given below.

• Voltmeter − Voltmeter is used to measure the voltage in the circuit.

• Ammeter − The ammeter is used to measure the current in the circuit.

• Electric bulb − The symbol for the electric bulb is given below.

Conclusion

This article explained the concept of electric circuits and the history of circuits and systems in detail. The components of an electric circuit and the symbols used for different electrical components are also discussed.

FAQs

1. What is a simple circuit?

Generally, the circuit is a closed path where current passes through it. A simple circuit is a circuit that contains some basic elements such as a voltage source, conducting path, and load resistor.

2. Why should we use a fuse?

Fuse is used to protect the electric circuits and appliances from short circuits or overloading. It is made of a wire whose resistance is high and melting point is low. Due to this whenever the current passes through the circuit is high the fuse wire gets melted and the circuit breaks. This stops the flow of current through the circuit and saves the electrical appliances from damage.

3. What are the characteristics of an electric circuit?

There must be a return path in the electric circuit as it is a closed loop. In every electric circuit, there should be at least one power source. That is it should contain at least one active element. Electric circuits contain both active and passive elements connected in series or parallel. In an electric circuit, the electron flows from the negative terminal to the positive terminal.

4. What are the uses of circuit diagrams?

Circuit diagrams are very much useful in understanding electric circuits. The main use of circuit diagrams is to construct and maintain electric and electronic circuits. It explains clearly the arrangements of electronic components in the circuit to construct a circuit.

5. What are complex circuits?

The circuits in which the components are connected in series as well as in parallel is called a complex circuit.