Discovered in 1827 by the German physicist Georg Simon Ohm (1789-1854), Ohm’s Law is one of the laws of greatest importance in the governance of electrical and electronic circuits.
It is a fundamental principle that all electronics engineers should understand, not least because it is one of the few formulas that such professionals will regularly use.
So, What Actually Is Ohm’s Law?
Ohm’s Law shows the mathematical relationship between voltage, current, and resistance.
To give a more precise definition, Ohm’s Law states that the current flowing in a circuit is directly proportional to the applied potential difference, and inversely proportional to the resistance in the circuit.
This relationship between the three metrics is demonstrated by a simple formula, such that if two of these circuit quantities are known, the remaining one can be easily worked out.
This means, then, that Ohm’s Law can be mathematically expressed as any of the following, where I is the current in amperes, V is the current in volts, and R is the resistance in ohms:
- V = I x R
- R = V / I
- I = V / R
A modern electronics engineer may perform any of these calculations manually. They may also use a reputable Ohm’s Law calculator online to help speed up the process, or to verify the accuracy of their manual workings-out.
Understanding Ohm’s Law
To make the concept of Ohm’s Law more relatable, a novice engineer may be advised to imagine the electrical situation as akin to the flow of water in a pipe.
In this analogy, the voltage is represented by the water pressure in the pipe. The current, meanwhile, is the equivalent of the amount of water flowing through the pipe, while the resistance is represented by the size of the pipe.
It can be easily understood that:
- Having a wider pipe would cause a greater amount of water to flow, because it is easier for more water to flow through a wider pipe than a narrower one.
- If a narrower pipe was chosen, this would present greater resistance to the flow of water.
- Alternatively, the decision could be made to keep the pipe the same dimension, but to increase the pressure into the pipe. This would result in more water flowing.
In What Ways Is Ohm’s Law Applied in Electronics Today?
When it comes to the design and analysis of circuits in all manner of devices like computers, smartphones, and power supplies, Ohm’s Law plays a critical role.
Here are some of the common applications of Ohm’s Law in modern electronics:
• Circuit Design
It is crucial to ensure components such as LEDs and microchips always operate within safe limits. To this end, engineers make routine use of Ohm’s Law to calculate resistor values that are appropriate for controlling current and voltage in circuits.
• Power Calculations
The power formula P = V x I can be used to figure out the level of power dissipation in components. This can be vital in electronics projects like power supplies or amplifiers, for ensuring components are selected that can handle the power and won’t overheat.
• Troubleshooting
The measurement of voltage, current, or resistance is also done by technicians in their work to diagnose circuit faults. For example, a circuit having unexpectedly low current might be a sign of high resistance, attributable to a loose connection or a damaged component.
The Importance of Ohm’s Law Should Never Be Underestimated
Whether your own projects focus on simple circuits or much more advanced technologies, the bottom line is that you will need to know about – and understand – Ohm’s Law. It is a cornerstone principle in the design and construction process for today’s electronic systems.
