Ohm’s Law – Explained

What is Ohm’s Law?

Ohm’s Law is a basic principle in electricity that explains how voltage, current, and resistance are related in an electrical circuit. It tells us how one of these factors affects the others.

The Formula

Ohm’s Law is expressed with the following formula:

$$V = I times R$$

Where:

• V = Voltage (measured in volts (V))
• I = Current (measured in amperes (A) or amps)
• R = Resistance (measured in ohms (Ω))

What Do These Terms Mean?

1. Voltage (V):
   • Voltage is like the pressure that pushes the electric current through the wires. It’s the force that moves the electrons around the circuit.
   • You can think of voltage as the water pressure in a pipe that pushes water through the system.
2. Current (I):
   • Current is the flow of electrons through the circuit. It’s like the amount of water flowing through a pipe.
   • The current is measured in amperes (amps). A higher current means more electrons are flowing.
3. Resistance (R):
   • Resistance is how much a material opposes the flow of electrons. It’s like the friction in a pipe that slows down the flow of water.
   • It’s measured in ohms (Ω). High resistance means it’s harder for the current to flow.

How Ohm’s Law Works

Now, let’s understand how voltage, current, and resistance are connected using Ohm’s Law.

• If you increase the voltage, more current will flow through the circuit (if the resistance stays the same).
• If you increase the resistance, less current will flow for the same amount of voltage.
• If you increase the current, it means either the voltage has been increased or the resistance has been lowered.

Simple Examples

1. Example 1: Changing Voltage
   • Imagine you have a light bulb with a resistance of 10 ohms (R = 10Ω), and the voltage across the bulb is 20 volts (V = 20V).
   • Using Ohm’s Law, you can calculate the current (I):
     $$I = frac{V}{R} = frac{20V}{10Ω} = 2A$$ 
   • So, the current flowing through the light bulb is 2 amps.
2. Example 2: Changing Resistance
   • If you use a different light bulb with a resistance of 5 ohms (R = 5Ω), but the voltage is still 20 volts (V = 20V), what happens?
   • Using Ohm’s Law:
     $$I = frac{V}{R} = frac{20V}{5Ω} = 4A$$ 
   • The current increases to 4 amps because the resistance is now lower.

What Does Ohm’s Law Tell Us?

• More Voltage = More Current (if resistance stays the same).
• More Resistance = Less Current (if voltage stays the same).
• More Current = Higher Voltage or Lower Resistance.

Easy Way to Remember

You can think of Ohm’s Law as a relationship between pressure (voltage), flow (current), and friction (resistance).

• If you increase the pressure (voltage), more water (current) flows.
• If you increase the friction (resistance), less water (current) can flow.

Summary

Ohm’s Law is a simple equation that helps you understand how voltage, current, and resistance relate to each other. The formula V = I × R tells you:

• Voltage (V) is equal to current (I) times resistance (R).
• If you change one of these values, you can predict how it affects the others.