[Physics Class Notes] on Electric Circuit Pdf for Exam

An electric circuit is a path through which electric current flows. An electric circuit can also be a closed path (in which the ends are joined), thereby making it a loop. The flow of electric current is possible because of the closed circuit. An electric circuit can also be an open circuit in which the flow of electrons is cut because the circuit is broken. Electric current doesn’t flow in an open circuit.

 

It is important to know about the basic parts of an electric circuit. A simple electric circuit contains a source, a switch, a load, and a conductor. The functions of these parts are:

● Cell: It is used as a source to supply electric current.

● Load: It is a resistor. It is basically a light bulb, which glows when the circuit is turned on.

● Conductors: Copper wires are used as conductors with no insulation. One end of the wire carries current from the power source to the load and the other end from the power source.

● Switch: It is a part of the circuit that controls the supply of current in the circuit. It is used to open or close the circuit.

 

Electric current and voltage are the two basic features of an electric circuit. Electric circuit analysis is a process in which current and voltage are determined in any element of the electric circuit.

 

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The above figure represents a simple electric circuit containing:

 

Due to the complete circuit, current I flows through the circuit, and a potential drop of V volts is developed across the resistor.

 

Types of Electric Circuits

There are two types of electric circuits.

• Series circuit.

• Parallel circuit.

 

Series Circuit

In a series circuit, there is only one path for the flow of electrons. The entire circuit is closed or open at the same time. No current flow in the circuit in case of a circuit break because the entire circuit is open; this is the major disadvantage of a series circuit. For example, if many light bulbs are connected in a series circuit, then if one light bulb goes out, the others will also turn off.

Parallel Circuit

In a parallel type of electric circuit, different parts of the circuit are connected across different branches. Hence, electron flow occurs in several parts. If in one path a circuit break occurs, electric current still flows in other paths. Household wiring of appliances are based on parallel circuits, so if one light bulb goes down, the other will still flow.

Domestic Electric Circuit

The above figure represents the domestic circuit diagram.

• The electric power that we receive in our houses is by the main supply, commonly called mains.

• It is supplied by either overhead cables or by underground cables.

• There are 3 types of wires in domestic circuits and are Earth Wire, Live Wire, and Neutral Wire.

• Earth Wire: The earth wire is generally green in color. It is connected with a metal plate buried in the ground near the house, to provide safety for the gadgets and appliances which have a metallic body. When a charge leak occurs in the metallic body, the charges are transmitted to the ground to prevent shocks and damage.

• Live Wire: It is the positive conductor or wire which is generally red in colour.

• Neutral Wire: It is the negative conductor or wire which is generally black in colour.

• The potential difference (or voltage) which is supplied in our country is 220V.

• The electric current of our house is first passed through a circuit called a Fuse. If any high voltage, overloading, voltage fluctuation or short circuit occurs, the fuse melts thereby restricting the current supply and preventing the high voltage from reaching the electric appliances.

• These wires are passed to different electric appliances of the house through the meter board.

• Generally, 2 types of electric circuits are used for household use:

• 15 A: Appliances that have higher power ratings. ( like geysers, ACs, refrigerators)

• 5 A: Appliances that have lower power ratings. ( like TV, fans, bulbs)
  

Basic Circuit Parts

As mentioned on top of, a circuit may be a hub of parts connected to every different. Circuit parts area units are classified into 2 parts, active or passive parts, in step with their capability to make energy.

1. Active Circuit parts

Active parts unit those parts that may generate energy on their own. for instance diodes, amplifiers, batteries, and generators. The supply parts area unit is the foremost crucial active part Of the associate electrical device.

Sources sort of a voltage or current area unit of 2 varieties that area unit freelance sources and Dependent sources. An electric battery is an associate freelance supply that has a continuing voltage to the circuit, regardless of this that’s passing through the terminals.

A semiconductor unit may be a supply that provides current to the circuit, semiconductor unit depends upon the facility applied thereto.

2. Passive circuit parts

Elements that may manage the flow of electrons through them are a unit referred to as Passive parts. they’re capable of either increasing or decreasing the voltage. Below are some samples of passive parts.

For a linear circuit, an electrical device opposes the flow of current through. Ohm’s law comes into the image, which states that voltage across the electrical device is directly proportional to this passing through it, the proportional constant being the resistance thereto.

The associate electrical device helps to store energy within the variety of the magnetic force field in order that the voltage across the associate electrical device is capable of the constant amendment of current passing through it.

An electrical condenser helps to store energy within the variety of the electric field conjointly, the voltage across an electrical condenser is capable of the charge.

What Area Unit associates an Electric Circuit and a Brief Circuit?

1. Short

The affiliation between 2 conductors with low resistance in an electrical circuit is named a brief circuit. you will have seen sparks and smoke thanks to the warmth made, that’s due to a brief circuit. Short circuits generate additional heat.

 

There are a variety of reasons for a brief circuit to occur in that area, some loose connections, defective insulation, faulty wires or chews by animals, and out-of-date electrical appliances. to forestall such dangerous situations, the simplest and normally used technique to forestall damages employing a fuse or an electrical fuse that stops short circuits.

2. Open Circuit

An interruption within the electrical device is the main reason behind the associated electric circuit. Unconnected parts {in a|during a|in associate exceedingly|in a very} circuit produces an electric circuit.

3. Circuit Protection

The addition of a weak link inside the associated electrical device is named circuit protection. The explanation behind the installation of a weak link is to forestall injury thanks to short circuits, and an associated extreme quantity of temperature. A fuse, switch logic gate breaker may be a circuit protection device. Studies show that thanks to circuit protection, such damages were reduced.

Electrical Safety

Studies show that quite 100 individuals die per annum thanks to electrical shock in their workplaces and around sixty individuals die per annum once obtaining an electrical shock from varied power tools and cables.

 

The reason to bring this up to you is to form individuals conscious of the security precautions and thumb rules that an area unit imagined being followed once operating with electricity. Electricity may be very dangerous to trot out and untrustiness will value your life. It’s common that individuals hump their phones on a charge, blocked in sockets. There are some WHO even place their phones on charge and so hump earphones in their ears. To heaps of individuals this won’t be an enormous deal, but, over the past few years, we’ve noticed and detected such a large amount of youth dying simply because of their cognitive content.

Precautions while using Electric Circuits

• Always use good quality wires which have proper insulation and thickness, for household wiring. Install products like plugs, switches, and sockets that have an ISI mark in them for better use of electrical appliances.

• The connections of the wires should be tight and completely insulated.

• You should always switch off the mains supply before starting any repair work of the electric circuit.

• If any short circuit or shock occurs, switch off the main supply at first. Then try to totally insulate the person who has received an electric shock. Do not touch him directly.

• While earthing or installing a fuse for the household electric circuits, you should take precautions.