Understanding Ohm's Law: A Comprehensive Guide

Ohm’s Law is a fundamental principle in electronics that explains how voltage, current, and resistance are related. But numbers alone can confuse beginners. So, let’s understand this using a simple analogy — a water tank, a pipe, and a gate wall.
🧠 What is Ohm’s Law?
Ohm’s Law states:
V = I × R
where:
V = Voltage (in volts)
I = Current (in amperes)
R = Resistance (in ohms)
This formula tells us:
The current flowing through a circuit is directly proportional to the voltage and inversely proportional to the resistance.
💧 Water Tank Analogy
Imagine a water tank at a height with a pipe at the bottom.
The water pressure inside the tank = Voltage (V)
The rate of water flow through the pipe = Current (I)
Any narrowing of the pipe or gate control = Resistance (R)
🚪 Gate Wall Analogy – Resistance in Action
Now, place a gate wall (valve) in the pipe that can be opened or closed to control the water flow.
Fully open gate → low resistance → water flows freely → high current
Partially closed gate → medium resistance → reduced water flow → medium current
Almost closed gate → high resistance → very little water flows → low current
This is exactly how a resistor works in an electrical circuit.
🔄 Understanding the Relationship Between V, I, and R
Let’s break it down further using real examples.
📌 Case 1: Fixed Resistance, Increase Voltage
Voltage (V) | Resistance (R) | Current (I = V / R) |
10V | 10Ω | 1A |
20V | 10Ω | 2A |
5V | 10Ω | 0.5A |
🔎 Observation: When resistance is constant, increasing voltage increases current — like adding more water pressure.
📌 Case 2: Fixed Voltage, Increase Resistance
Voltage (V) | Resistance (R) | Current (I = V / R) |
12V | 6Ω | 2A |
12V | 12Ω | 1A |
12V | 24Ω | 0.5A |
🔎 Observation: When voltage is constant, increasing resistance decreases current — like tightening the gate in the pipe.
💡 Key Takeaways
Voltage (V) is like water pressure
Current (I) is like the flow rate
Resistance (R) is like a valve or gate controlling flow
Ohm’s Law connects them: V = I × R
The more pressure, the more flow.
The tighter the gate (more resistance), the less water can pass (less current).
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Written by

Ravikirana B
Ravikirana B
I’m Ravikirana B – an engineer driven by curiosity and clarity. I specialize in electronics, Python programming, and work across a range of technologies to build real-world solutions that blend hardware and software. I started Tech Shodhaka to share what I learn, simplify what I know, and spark curiosity in those who want to understand how tech actually works — especially in our own languages and ways of thinking. Here, you’ll find: 🔧 Electronics concepts explained with analogies (like water flow, gates, tanks) 🐍 Python-based tech insights and automation ideas ⚡ Real tech reflections from both theory and hands-on work 🌿 A touch of Kannada-English expression for wider reach I believe in making learning accessible, especially for students and self-learners from smaller towns like mine. If you’re someone who loves understanding “why” and “how”, Tech Shodhaka is for you. Let’s keep exploring, clearly and curiously. 🙌