Ohms Law

Scientifically stated, it says: "The intensity Of the current in amperes in any electrical circuit is equal to the difference in potential in volts across the circuit divided by the resistance in ohms of the circuit." Simply put it means that current is equal to volts divided by ohms, or expressed as a formula, the law becomes:

or it can be written:

This is important because if you know any two of the quantities, the third may be found by applying the equation.

Ohm's law includes these two ideas:

1. In a circuit, if resistance is constant, current varies directly with voltage.

Now what this means is that if you take a component with a fixed resistance, say a light bulb, and double the voltage you double the current flowing through it. Anyone who has hooked a six-volt bulb to a twelve-volt circuit has experienced this. But it wasn't "too many volts" that burned out the bulb, it was too much current. More about that later.

2. In a circuit, if voltage is constant, current varies inversely with resistance.

This second idea states that when resistance goes up, current goes down. That's why corroded connectors cause very dim lights - not enough current.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook

Post a comment