# Chapter 3 – Current Electricity

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

Introduction

Electric current is an important concept that explains the passing of energy. The article will talk about current electricity and the factors that influence it.

Current electricity is a fundamental concept for students to understand how electricity works and the factors that affect the flow of electricity.  Here, we touch upon Ohm’s Law and resistivity along with the basics of current electricity.

Current per unit time is referred to as the passage of charge through an area. A closed-circuit is vital for a steady flow of electricity. Current electricity talks about the dynamic nature of electricity. The electric charge comes from an external source that moves to a higher potential from a lower potential. Electromotive force refers to the work done by a unit charge to move the charge.

#### Ohm’s Law

The Ohm’s Law states that the electric current that flows through a substance is directly proportional to the voltage present across ends. This electricity is carried by negatively charged particles, known as electrons. In some cases, these particles are also known as ionic crystals, electrolytic liquid, etc.

Ohm’s Law: Voltage = current x resistance. Some drawbacks of Ohm’s Law are:

• The voltage depends on the current. This relationship is non-linear, and it fails.
• The relationship between voltage and current is directly dependent on the sign of the voltage.
• Also, there is no unique relationship between current and voltage.

#### Kirchhoff’s Rules

There are specific rules that govern current electricity. Some of the laws are:

• If the sum of all the charges around the closed-loop is taken into consideration, the sum would be zero.
• When we take the bonding point of a circuit, the sum current entering the circuit would be equal to the sum of current leaving the same circuit.

#### Resistance and Resistivity

Resistance refers to the hindrances present in the electrical circuit that oppose the flow of current. It is measured in Ohms. Ohms is symbolised by the Greek symbol of Omega. With more resistance, the flow of electrons is reduced. If a material offers low resistance, the negatively charged particles can easily move through the substance. The resistance depends on the following 2 factors:

1. The material of the conductor.
2. The dimensions of the conductor.

Resistivity is the electrical resistance of a conductor. It talks about the resistance of a unit cross-sectional area and a unit length. The SI unit of resistance is Ohm meters. It is defined in terms of the magnitude of the electric field and the magnitude of current density which is measured in ampere per square metres. Materials like copper, silver, which are generally used as conductors have a low resistivity. However, in the case of insulators, the resistance is relatively high, thus obstructing the flow of electric current. These insulators include water, wood, etc.

#### Factors on which Resistivity Depends

Temperature Dependence of Resistivity is an established phenomenon. Given below are some of the factors on which resistivity depends:

• Length: The length of the wire plays a significant role. When the length of the wire is increased, the resistivity of the substance tends to increase.
• Thickness: When the thickness of the wire is increased, the resistivity of the substance is brought down.
• Temperature: An increase in temperature is known to increase the resistivity of the medium, hence hindering the free flow of electrons.

Origin of Resistivity

Resistivity comes into picture when current is passed through the substance. Due to this current, the drift of electrons takes place, which influences resistivity; the particles suffer collisions bringing resistivity into the picture. Also, the drift velocity’s direction to the conduction electrons will always be opposite to the electric field direction. Superconductivity

A  noteworthy phenomenon, Superconductivity is observed when the electric current moves through a substance without facing any electrical resistance. This is a situation of perfect efficiency as the current gets passed from one point to another without any resistance. This also means that the velocity of electricity is not disrupted and there is no loss of energy that takes place on the way from one point to another point of the circuit.

#### What is a Potentiometer?

The device used for measuring the potential difference between two points is known as the potentiometer.

Alternatively, this device can also be effectively used to measure the internal resistance that is present in a circuit. Also, it helps in measuring the difference between two points within the circuit.

#### Resistors in Series and Parallel

1. Series
In case of a series circuit, the resistors are connected in a series, i.e. beside each other. Here, the output from one resistor immediately becomes the input current of another resistor. All these are connected in a line.
2. Parallel
In the case of parallel resistors or resistors connected in parallel, each resistor experiences the same drop in the electricity. These resistors are connected but on different sides. Here, the current flowing through different resistors can be different. The voltage remains the same, but the electricity flow differs in all the resistors connected parallelly.

There is a sequential flow of electricity when the resistors are connected in a series. There is only one path that is followed by the electricity. However, in the case of the parallel circuits, electricity gets divided into different paths and flows separately across channels.

Understanding the concept of current electricity is essential to learn how electricity flows from one point to another. Also, another critical aspect of it is it will help you in building circuits. Electric current is a free charge that moves from a body of higher potential to a body having low potential. Learn more concepts on electricity with real life examples on the MSVgo app.

### 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
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• Light – Reflection And Refraction
• Magnetic Effects Of Electric Current
• Magnetism and Matter
• Management Of Natural Resources
• Mechanical properties of Fluids
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• Motion
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• Motion in a straight line
• Moving Charges and Magnetism
• Nuclear Energy
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• Our Environment
• Paths of Heat
• Physical world
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• Semiconductor Devices
• Semiconductor Electronics: Materials, Devices and Simple Circuits
• Simple Machines
• Sound
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• Specific and Latent Heats
• Spherical Mirrors
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• Systems of Particles and Rotational motion
• Thermal properties of matter
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• 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
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• Basic concepts of Chemistry
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• Carbon And Its Compounds
• Carboxylic acids and Acid Derivatives
• Chemical Bonding and Molecular Structures
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• Chemistry in Everyday Life
• Chemistry of p-Block elements
• Chemistry of Transition and Inner Transition
• Classification of Elements
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• Electrochemistry
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• The d-block and f-block elements
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### High School Biology

• Absorption and Movement of Water in Plants
• Anatomy of Flowering Plants
• Animal Kingdom
• Bacteria and Fungi-Friends and Foe
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• Biological Classification
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• Diversity In Living Organisms
• Ecosystem
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• Flowering Plants
• Genes and Chromosomes
• Health and Diseases
• Health and Its Significance
• Heredity And Evolution
• Heredity and Variation
• How Do Organisms Reproduce?
• Human Diseases
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• Improvement In Food Resources
• Integumentary System- Skin
• Kingdom Fungi
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• 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
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• 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
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• Calculus – Continuity and Differentiability
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• Geometry – Area
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• Geometry – Introduction to Euclid’s Geometry
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• Linear Programming
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• Mensuration – Areas
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• Number Systems
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• 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