The Truth About Ohm’s Law: What They Don’t Teach You
In this Class 12 Physics lecture, Brightminds Tuition Centre, Trichy explains the limitations of Ohm’s Law in a simple, conceptual, and exam-oriented manner.
Ohm’s Law states that the current flowing through a conductor is directly proportional to the potential difference across it, provided temperature and other physical conditions remain constant.
However, Ohm’s Law is not universally applicable. Many electrical devices and materials do not maintain a constant resistance and therefore do not obey Ohm’s Law.
📚 Topics Covered:
⚡ What is Ohm’s Law?
⚡ Conditions Required for Ohm’s Law
⚡ Meaning of Ohmic Conductor
⚡ Meaning of Non-Ohmic Conductor
⚡ Limitations of Ohm’s Law
⚡ Effect of Temperature on Resistance
⚡ Why Filament Bulbs Do Not Obey Ohm’s Law
⚡ Semiconductor Devices
⚡ Diodes and Transistors
⚡ Electrolytes
⚡ V-I Characteristics
⚡ Linear and Non-Linear V-I Graphs
⚡ Important Board & NEET Concepts
🎯 Important Formula
V = IR
Where:
V = Potential Difference
I = Electric Current
R = Resistance
Important Condition
Ohm’s Law is valid only when temperature and other physical conditions of the conductor remain constant.
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❌ Limitations of Ohm’s Law
Ohm’s Law does not apply when:
🔹 Temperature of the conductor changes
🔹 Resistance changes with current or voltage
🔹 The V-I graph is non-linear
🔹 Current flows through semiconductor devices
🔹 Current flows through electrolytes
🔹 Devices such as diodes, transistors and filament lamps are used
🎓 Useful For
✅ CBSE Class 12 Physics
✅ NCERT Class 12 Physics
✅ Tamil Nadu State Board
✅ Samacheer Kalvi Physics
✅ NEET Physics
✅ JEE Physics Basics
✅ Board Examinations
✅ Competitive Exams
📍 Brightminds Tuition Centre, Trichy
📖 Subject: Physics
🎓 Class: Class 12
📘 Chapter: Current Electricity
⚡ Topic: Limitations of Ohm’s Law