NEETClass 11thClass 12thClass 12th PlusJEEClass 11thClass 12thClass 12th PlusClass 6-10Class 6thClass 7thClass 8thClass 9thClass 10thOnline CoursesDistance LearningInternational OlympiadNEETClass 11thClass 12thClass 12th PlusJEE (Main+Advanced)Class 11thClass 12thClass 12th PlusJEE MainClass 11thClass 12thClass 12th PlusClass 6-10Class 6thClass 7thClass 8thClass 9thClass 10thKCET/MHT-CETKCETMHT-CETNEET2025202420232022JEE20262025202420232022Class 6-10JEE MainPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DatePercentile PredictorAnswer KeyCounsellingEligibilityExam PatternJEE MathsJEE ChemistryJEE PhysicsJEE AdvancedPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DateAnswer KeyEligibilityExam PatternRank PredictorNEETPrevious Year PapersSample PapersMock TestResultAnalysisSyllabusExam DateCollege PredictorAnswer KeyRank PredictorCounsellingEligibilityExam PatternBiologyNCERT SolutionsClass 6Class 7Class 8Class 9Class 10Class 11Class 12TextbooksCBSEClass 12Class 11Class 10Class 9Class 8Class 7Class 6SubjectsSyllabusNotesSample PapersQuestion PapersICSEClass 10Class 9Class 8Class 7Class 6State BoardBiharKarnatakaMadhya PradeshMaharashtraTamilnaduWest BengalUttar PradeshOlympiadMathsScienceEnglishSocial ScienceNSOIMONMTCASATInstant Online ScholarshipAIOT(NEET)TALLENTEXALLEN for SchoolsAbout ALLENBlogsNewsCareersRequest a call backBook a demo
Electric Resistance and Ohm's Law
Master Circuit Dynamics in Minutes: Discover how electric current flows through a conductor and encounters opposition. Master the foundational principles of Ohm's Law, the physical parameters that dictate electrical resistance, and how to read V-I graphs without complex vector calculus or multi-layered code blocks.
1.0Learning Outcomes
After completing this lesson, you will be able to:
- State Ohm's Law and its mathematical boundary conditions.
- Define electrical resistance and its standard SI unit.
- Graph and interpret Voltage vs. Current (V-I) characteristic slopes.
- Identify the four major physical factors that dictate a conductor's resistance.
- Differentiate between resistance and material resistivity.
2.0Electric Resistance
The property of a material which offers opposition to the electric current and dissipates energy is called its ‘electric resistance’.
The ratio of applied potential difference (voltage) to the resulting electric current in a closed circuit is called ‘electric resistance’.
Unit of Resistance
SI unit : ohm (Ω)
1 ohm = 1 volt/ampere or 1 Ω = 1 V A–1
Definition of 1 ohm
When the potential difference of 1 volt is applied across the ends of a conductor and the current produced in it is 1 ampere, then the resistance of the conductor is 1 ohm.
Voltage and Resistance
See the water filled bucket in the figure below. The raised water has energy that is lost when the water falls. Increasing the height from which the water falls increases the energy of the water.
Increasing the height of the water is similar to increasing the voltage of the battery. Just as the water current increases when the height of the water increases, the electric current in a circuit increases as voltage increases.
3.0Ohm’s law
(given by German physicist George Simon Ohm in 1827)
According to Ohm’s law, ‘the current through certain conductors is directly proportional to the potential difference between its ends at a constant temperature’.(see figure (a) and (b))
or Where, R is constant called resistance of the conductor.
Ohm’s law is not a fundamental law, it is only an empirical law that holds approximately good for many substances particularly metals. (see figure)
4.0Electric Circuits
A continuous path which consists of various electric devices like bulb, tube light, resistors, etc. connected with each other through conducting wires to the terminals of a source of voltage like battery is called electric circuit.
Circuit elements
The various devices like electric bulbs, resistors, etc. connected in an electric circuit are called circuit elements. (see figure)
Circuit diagram
A diagram which indicates how different devices are connected in a circuit by using proper electric symbols for the devices is called a circuit diagram.
Symbols of some commonly used components in circuit diagrams
1. If the current in a household appliance is 5 A, calculate the amount of charge that passes through the appliance in 1 hour.
Solution
Given, current, I = 5 A ; time, t = 1 h = 3600 s ; charge. Q=?
Now, charge, Q = I × t = 5 × 3600 = 18000 C = 1.8 × 104 C
2. In a particular television tube, a beam of electrons is emitted. The beam current is 80 μA. How many electrons strike the screen of TV every second? Also find the total charge striking the screen in 2 minutes.
Solution
Here, I = 80 μA= 80 × 10–6 A = 8 × 10–5 A
(i) t = 1 second
Using, , we get
(Q e = 1.6 × 10–19 C)
∴ 5 × 1014 electrons strike the screen every second.
(ii) Also,
∴ Q = It = 8 × 10–5 A × 2 minutes = 8 × 10–5 A × 2 × 60 seconds
= 960 × 10–5 C = 9600 × 10–6 C = 9600 μC
5.0EUREKA by ALLEN – The Future of Class 10 Learning
With EUREKA by ALLEN, you're going to change the way you learn as a Class 10 student using an AI-based educational platform designed just for you! EUREKA offers everything from online videos, customized learning paths, immediate question resolution, and live statistics about how well you are doing with ALLEN's educational professional discipline combined with advanced technology for a more intelligent and effective learning experience!
Key Features:
- AI-enabled doubt solving 24/7
- Interactive and personalized learning experience
- Story-led concept explanations
- Board exam-focused question practice
- Instant assessments and feedback
- Smart progress reports
- NCERT and CBSE syllabus coverage
- Flexible self-paced learning
- Expert faculty mentorship
6.0Supporting Study Materials
This study material, including CBSE Notes and NCERT Solutions for the Chapter "Electricity" on Electric Resistance and Ohm's Law topics, is designed according to the latest CBSE Class 10 Science syllabus and NCERT guidelines. It provides clear explanations of key concepts, definitions, graphs, mathematical derivations, and important numerical questions to help students understand potential difference, Ohm's law, resistance, factors affecting resistance, and resistivity, and prepare effectively for examinations.
7.0Previous Year Question
1. List the factors on which the resistance of a uniform metallic conductor depends. How does resistivity differ from resistance? (CBSE Board)
Answer: Factors Affecting Resistance: The electrical resistance of a uniform metallic conductor depends on:
- Its total length
- Its cross-sectional area
- The nature of the material used
- The operating temperature of the conductor
Difference Between Resistance and Resistivity:
- Resistance is a property of a specific object or component that scales directly with its length and thickness. Its SI unit is the Ohm
- Resistivity is an intrinsic characteristic property of the material itself. It remains constant regardless of changes to the wire's length or cross-sectional area. Its SI unit is the Ohm-meter.
8.0Recommended Next Topics
- Resistors in Series Combination circuits
- Resistors in Parallel Combination circuits
- Heating Effects of Electric Current (Joule's Law)
- Electric Power and Commercial Units of Energy