# Chapter 5 – Electric Current and Circuit

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

We haven’t seen it, but we have felt its presence due to all the smaller or bigger gadgets that we use in our everyday lives. Did you guess it? Yes, it’s electric current!

Here, we will talk about the electric current that is our regular need. We can’t even think of our lives without it. Below are the basics of electricity and the electric current that you must know. Let’s go through it.

#### What are Electric Current and Electric Circuit?

We know there is something in these wires that is continuously flowing and providing us with the electricity.

Electric current is the rate of continuous and random flow of electrons at any given point in the circuit. In short, the flow of electric charge is current. Electric current, having SI unit ampere(A), can be measured as the net flow over a region by an instrument called an ammeter.

The electric circuit is the path for these particles to flow. The circuit path has an opening as ‘source’ and closing as ‘earth ground’. It can be a device, battery, or generator.

#### Atomic Structure

The whole atom consists of 3 elements distributed in two regions, the inner and orbital. Protons, neutrons, and electrons are the three basic particles in an atom. Proton elements containing the positive charge lie in the nucleus along with the neutral charge element neutron. Thus the centre part of the atom, which is the nucleus, has a positive charge. Negatively charged electrons revolve in the orbits around the nucleus in the centre.

You can calculate the atomic mass of any element by knowing the number of protons or neutrons in it. The same mass particles Protons and neutrons weigh approximately about 1.67 × 10-24 grams. Thus neutrons having no charge contribute to atomic mass but not to atomic charge. Electrons have 9.11 × 10-28 grams weight, which is only 1/1800 of an atomic mass unit.

#### Conductors and Insulators

There are materials that we know on wearing that help us against electric current. On the contrary, some materials are very good for electricity to flow and get a good current.

Conductors are those materials that allow easy electron flow in them and transfer charge through it. On providing charge to a precise location on conducting material, it spreads over the whole surface as the electron flows and charge is transferred. The charge can also be passed to another conducting material on bringing them in contact.

While Insulators, opposite to it, are the materials that resist this movement of electrons in free space. The given charge at any location on the insulating material remains there only and does not spread over completely.

#### Models of Electric Current

The model described in the form of a mathematical expression, or setting the equivalent device in the manner that it behaves as the required one for the electrical circuit, is known as the electrical model.

There are various ways to explain this using numerous devices and tricks for the classroom or anywhere.

#### Drift Velocity of Electron

Drift Velocity is the average velocity attained by charged particles (electrons) in a material due to an electric field. The average velocity mostly results in zero because of the random direction movement of electrons. On applying an electric field, these randomly moving electrons slowly align in one direction. Thus drift velocity is the velocity at which electrons are brought in the same direction.

I=nAvQ

where

I is current,

N is the number of electrons,

A is the cross-sectional area of the conductor,

V is drift velocity, and

Q is the charge.

#### Electric Circuit

An electrical circuit is a complete path for the electron to flow – starting from the source from where it enters to the earth ground or return point where it leaves the circuit. The whole path in between these two points is known as load.

The electric circuit can use either AC or DC power sources. It can be as simple as lighting a bulb or complicated as a microprocessor in a computer with various elements such as resistors, capacitors, transistors, and much more.

Electrical circuits can mainly be of four types:

1) Series Circuit: The current in the path of the circuit remains constant as there is only one way to flow.

2) Parallel Circuit: The current gets distributed as there is more than one way for the current to flow.

3) Open Circuit: They have one end of the circuit open and thus current cannot flow continuously or return to the source point.

4) Closed Circuit: They provide a closed path for current to flow between two ends.

#### Resistance and Ohm's Law

To explain the relationship between resistance, voltage, and current, Ohm’s law states that the current through a conductor is directly proportional to the voltage across the conductor. This means that as the current in the circuit increases due to less resistance, voltage gradually increases.

The formula is

Voltage= Current×Resistance

or

V = I×R

where

V = voltage,

I = current, and

R = resistance

Resistance has SI unit ohms and is denoted by Ω.

The basic application for this law is to determine either of these 3 quantities when the other two are provided for any given linear circuit.

#### Electric Power and AC

The rate at which the energy is consumed in any circuit is known as Electric Power. On the variation of time, power also varies. At any instance of time, the amount of power is known as instantaneous power. Power is the product of Voltage (V) and current (I) for any given circuit or component.

P = V x I

From this equation, it is sure that power can only be obtained when both voltage and current are present, not keeping open or closed circuits condition into consideration.

At a glance, the electric current is the flow of charges that we cannot see, but can surely feel it’s presence and thus the various quantities and components that are related to it need to be understood concisely through different ways.

#### FAQs

1. What is electric current and circuit?
• The flow of electric charge is current. The electric circuit is the path for these particles to flow.
1. What is the difference between the electric circuit and electric current?
• The electric circuit is the arrangement of various components in series or parallel sequence while the electric current is the flow of electric charge through these arrangements.
1. What are the four types of circuits?
• The main four types of electric circuit are open which is open from one end, closed circuit which has closed path, series in which the components are arranged linearly, and parallel circuits have more than one path for current to flow.
1. What is the flow of an electric charge called?
• Electric Current
1. Why are circuits needed for electricity to flow?
• Circuits provide a path for current to flow between two ends by connecting them.

Getting this all explained only through reading seems quite confusing, doesn’t it? You can go through the explanatory videos and animations on MSVGo. Check out the videos there and get a detailed understanding of the concepts behind them.

### High School Physics

• Alternating Current
• Atoms
• Communication Systems
• Current Electricity
• Dual nature of Radiation and Matter
• Electric Charges and Fields
• Electricity
• Electromagnetic Induction
• Electromagnetic Waves
• Electrons and Photons
• Electrostatic Potential and Capacitance
• Fluid Pressure
• Force and Acceleration
• Force And Laws Of Motion
• Gravitation
• Internal Energy
• Kinetic Theory
• Law of motion
• Light – Reflection And Refraction
• Magnetic Effects Of Electric Current
• Magnetism and Matter
• Management Of Natural Resources
• Mechanical properties of Fluids
• Mechanical properties of Solids
• Motion
• Motion in a plane
• Motion in a straight line
• Moving Charges and Magnetism
• Nuclear Energy
• Nuclei
• Oscillations
• Our Environment
• Paths of Heat
• Physical world
• Ray optics and optical instruments
• Semiconductor Devices
• Semiconductor Electronics: Materials, Devices and Simple Circuits
• Simple Machines
• Sound
• Sources Of Energy
• Specific and Latent Heats
• Spherical Mirrors
• Static Electricity
• Systems of Particles and Rotational motion
• Thermal properties of matter
• Thermodynamics
• Units and Measurement
• Vectors, Scalar Quantities and Elementary Calculus
• Wave Optics
• Waves
• Work, Power and Energy

### High School Chemistry

• Acids, Bases and Salts
• Alcohols, Phenols and Ethers
• Aldehydes, Ketones and Carboxylic Acids
• Aliphatic and Aromatic Hydrocarbons
• Alkyl and Aryl Halides
• Amines
• Analytical Chemistry
• Atomic Structure
• Atoms And Molecules
• Basic concepts of Chemistry
• Biomolecules
• Carbon And Its Compounds
• Carboxylic acids and Acid Derivatives
• Chemical Bonding and Molecular Structures
• Chemical Energetics
• Chemical Equilibria
• Chemical Kinetics
• Chemical Reactions And Equations
• Chemical Reactions and Their Mechanisms
• Chemistry in Everyday Life
• Chemistry of p-Block elements
• Chemistry of Transition and Inner Transition
• Classification of Elements
• Coordination Compounds
• Cyanide, Isocyanide, Nitro compounds and Amines
• Electrochemistry
• Electrolysis
• Elements, Compounds and Mixtures
• Environmental Chemistry
• Equilibrium
• Ethers and Carbonyl compounds
• Haloalkanes and Haloarenes
• Hydrocarbons
• Hydrogen
• Ideal solutions
• Introduction to Organic Chemistry
• Ionic equilibria
• Matter
• Matter Around Us
• Matter In Our Surroundings
• Metallurgy
• Metals And Non-Metals
• Mole Concept and Stoichiometry
• Natural Resources
• Organic Chemistry – Basic Principles
• Periodic Classification of Elements
• Physical and Chemical Changes
• Physical and Chemical Properties of Water
• Polymers
• Preparation, Properties and Uses of Compounds
• Principles and Processes of Isolation of Elements
• Redox Reactions
• Relative Molecular Mass and Mole
• States of Matter
• Structure Of The Atom
• Study of Compounds
• Study of Gas Laws
• Study of Representative Elements
• Surface Chemistry
• The d-block and f-block elements
• The Gaseous State
• The p-Block Elements
• The Periodic Table
• The s-Block Elements
• The Solid State
• Thermodynamics

### High School Biology

• Absorption and Movement of Water in Plants
• Anatomy of Flowering Plants
• Animal Kingdom
• Bacteria and Fungi-Friends and Foe
• Biodiversity and Conservation
• Biofertilizers
• Biological Classification
• Biomedical Engineering
• Biomolecules
• Biotechnology and its Applications
• Biotic Community
• Body Fluids and Circulation
• Breathing and Exchange of Gases
• Cell – Unit of Life
• Cell Cycle and Cell Division
• Cell Division and Structure of Chromosomes
• Cell Reproduction
• Cellular Respiration
• Chemical Coordination and Integration
• Circulation
• Control And Coordination
• Crop Improvement
• Digestion and Absorption
• Diversity In Living Organisms
• Ecosystem
• Environmental Issues
• Excretory Products and their Elimination
• Flowering Plants
• Genes and Chromosomes
• Health and Diseases
• Health and Its Significance
• Heredity And Evolution
• Heredity and Variation
• How Do Organisms Reproduce?
• Human Diseases
• Human Eye And Colourful World
• Human Health and Disease
• Human Population
• Human Reproduction
• Hygiene
• Improvement In Food Resources
• Integumentary System- Skin
• Kingdom Fungi
• Kingdom Monera
• Kingdom Protista
• Life Processes
• Locomotion and Movement
• Microbes in Human Welfare
• Mineral Nutrition
• Molecular Basis of Inheritance
• Morphology of Flowering Plants
• Neural Control And Coordination
• Nutrition in Human Beings
• Organism and Population
• Photosynthesis
• Photosynthesis in Higher Plants
• Plant Growth and Development
• Plant Kingdom
• Pollination and Fertilization
• Pollution; Sources and its effects
• Principles of Inheritance and Variation
• Reproduction and Development in Angiosperms
• Reproduction in Organisms
• Reproductive Health
• Respiration in Human Beings
• Respiration in Plants
• Respiratory System
• Sexual Reproduction in Flowering Plants
• Strategies for Enhancement in Food Production
• Structural Organisation in Animals
• Structural Organisation of the Cell
• The Endocrine System
• The Fundamental Unit Of Life
• The Living World
• The Nervous System and Sense Organs
• Tissues
• Transpiration
• Transport in Plants

### High School Math

• Algebra – Arithmatic Progressions
• Algebra – Complex Numbers and Quadratic Equations
• Algebra – Linear Inequalities
• Algebra – Pair of Linear Equations in Two Variables
• Algebra – Polynomials
• Algebra – Principle of Mathematical Induction
• Binomial Theorem
• Calculus – Applications of Derivatives
• Calculus – Applications of the Integrals
• Calculus – Continuity and Differentiability
• Calculus – Differential Equations
• Calculus – Integrals
• Geometry – Area
• Geometry – Circles
• Geometry – Conic Sections
• Geometry – Constructions
• Geometry – Introduction to Euclid’s Geometry
• Geometry – Three-dimensional Geometry
• Geometry – Lines and Angles
• Geometry – Straight Lines
• Geometry – Triangles
• Linear Programming
• Matrices and Determinants
• Mensuration – Areas
• Mensuration – Surface Areas and Volumes
• Number Systems
• Number Systems – Real Numbers
• Permutations and Combinations
• Probability
• Sequence and Series
• Sets and Functions
• Statistics
• Trignometry – Height and Distance
• Trignometry – Identities
• Trignometry – Introduction

### Middle School Science

• Acids, Bases And Salts
• Air and Its Constituents
• Basic Biology
• Body Movements
• Carbon and Its Compounds
• Cell – Structure And Functions
• Changes Around Us
• Chemical Effects Of Electric Current
• Coal And Petroleum
• Combustion And Flame
• Components Of Food
• Conservation Of Plants And Animals
• Crop Production And Management
• Electric Current And Its Effects
• Electricity And Circuits
• Elements and Compounds
• Fibre To Fabric
• Food production and management
• Force And Pressure
• Forests: Our Lifeline
• Friction
• Fun With Magnets
• Garbage In, Garbage Out
• Getting To Know Plants
• Health and Hygiene
• Heat
• Hydrogen
• Life Processes: Nutrition in Animals and Plants
• Materials: Metals And Non-Metals
• Matter and Its States
• Metals and Non-metals
• Micro Organisms: Friend And Foe
• Motion And Measurement Of Distances
• Motion And Time
• Nutrition In Animals
• Nutrition In Plants
• Organization in Living Things
• Our Environment
• Physical And Chemical Changes
• Pollution and conservation
• Pollution Of Air And Water
• Reaching The Age Of Adolescence
• Reproduction In Animals
• Reproduction In Plants
• Respiration In Organisms
• Rocks and Minerals
• Separation Of Substances
• Simple Machines
• Soil
• Some Natural Phenomena
• Sorting Materials Into Groups
• Sound
• Stars And The Solar System
• Structure of Atom
• Synthetic Fibers And Plastics
• The Living Organisms And Their Surroundings
• Transfer of Heat
• Transformation of Substances
• Transportation In Animals And Plants
• Universe
• Waste-water Story
• Water: A Precious Resource
• Weather, Climate And Adaptations Of Animals To Climate
• Winds, Storms And Cyclones

### Middle School Math

• Area and Its Boundary
• Boxes and Sketches
• Data Handling
• Fun With Numbers
• Heavy and Light
• How Many
• Long And Short
• Mapping
• Measurement
• Money
• Multiplication and Factors
• Multiply and Divide
• Numbers
• Parts and Wholes
• Pattern Recognition
• Patterns
• Play With Patterns
• Rupees And Paise
• Shapes And Angles
• Shapes And Designs
• Shapes and Space
• Similarity
• Smart Charts
• Squares
• Subtraction
• Tables And Shares
• Tenths and Hundredths
• Time