Ohm’s Law

Ohm’s law is one of the basic laws in physics that has multiple applications in the working of big and small machines. It helps establish a clear and concise relationship between the electric circuit’s current, voltage, and resistance. Georg Simon Ohm discovered that an electric current flowing through a resistor is directly proportional to the applied voltage. He published his work in 1827, which later formed one of the fundamental principles of electromagnetism. The law is extremely useful in electrical or electronic engineering as it correlates voltage, current and resistance in one simple equation. In this section, we will learn all about Ohm’s law, its applications, how it is verified, and about the water pipe analogy.

What is Ohm’s law?

Ohm’s law states that the voltage across a current carrying conductor is directly proportional to the current flowing through it if all physical conditions and temperature remain constant. Mathematically, it can be expressed as: V= I × R Where V is voltage I is the current R is the resistance offered by the conductor

What is Ohm’s law magic triangle?

It becomes difficult to learn the different relations of V- voltage, I- current, and R- resistance. Hence, there needs to be a solution that helps quickly solve all equations involving V, I, and R. It is the Ohm’s law magic triangle that comes handy while establishing the relations between V, I, and R. If the values of I and R are given, V can be evaluated by multiplying both I and R. If the values of V and I are given, V/I gives the value of R. If the values V and R are provided, I can be evaluated by V/R. Hence, one simple triangle helps students solve any numerical problem related to voltage, current, and resistance. As electrical power can be calculated using Ohm’s law. this triangle can derive the famous power triangle that is mentioned below:

How to verify Ohm’s law:

A simple electrical circuit experiment is required to verify Ohm’s law. Procedure:

• A nichrome wire is connected to a circuit with a voltmeter and ammeter.
• After passing a current through the wire, the potential difference and electric current are measured using the voltmeter and ammeter, respectively.
• The ratio of potential difference/ electric current is calculated.
• The current is increased, and the potential difference/ electric current ratio is measured again.
• Note that this ratio will remain equal for both times.
• Hence, Ohm’s law is verified.

What is the water pipe analogy for Ohm’s law?

Ohm’s law can also be understood using a simple mechanism of water flowing through a pipe. The pipe is analogous to the closed electric circuit. The water flow inside the pipe is similar to the amount of current flowing through the circuit. On increasing the pressure of the water pump, the rate of the water flowing will also increase through the pipe. The same observation is also valid in an electric circuit. On increasing the potential difference, the flow of electrons also increases, increasing the current in the circuit. On measuring the increasing and decreasing voltage and current values, the resistance present will remain constant. Below is the table describing the similar nature of the water pipe and the electric circuit.

Water-pipe circuit	Electric circuit
Increase in Pressure	Increase in Voltage
Increase of Flow rate	Increase of Current
Resistance measured is constant	Resistance measured is constant

Applications of Ohm’s law:

The major applications of Ohm’s law include:

• Ohm’s law can be used to choose a fuse. The current in a fuse is measured with the help of Ohm’s law if you know the resistance.
• Ohm’s law measures the amount of current that can be passed through the electric heater.

Limitations of Ohm’s law:

Although Ohm’s law is popular in electrical circuits, this law has certain limitations. Some of the main observed limitations of Ohm’s law include:

• First, it doesn’t hold good for non-linear electrical devices. The parameters like resistance and capacitance never abide by the linearity of the voltage and current, and hence Ohm’s law does not apply to these electrical elements.
• It does not apply to unilateral networks. These elements allow current to pass in one direction only, and hence Ohm’s law doesn’t hold good for these elements. Examples of such unilateral devices are transistors and diodes.

Conclusion

So, this is all about the basic Ohm’s law as verified by Georg Simon Ohm, a German physicist. It is an empirical law that describes the conductivity of the majority of charge carriers over the current magnitude. The material that doesn’t follow Ohm’s law is termed non-Ohmic. It is easy to understand this law after knowing the factors affecting the current and voltage value in the system. Moreover, the established verification of Ohm’s Law confirms the other generalizations of the law.