Limitations of Ohm’s Law

Ohm’s law may be defined as follows: It connects three physical phenomena: current, voltage, and resistance. German scientist George Simon Ohm established this link. Because of this, Ohm’s law is widely recognized. In simple terms, it asserts that the quantity of continuous current flowing through a large number of materials is precisely proportional to the difference in potential, or voltage, between those materials. The voltage V (measured in volts) between two ends of a wire made from one of these materials triples when the current I (measured in amperes) between the ends of the wire triples; however, the quotient V/I remains constant when the voltage V (measured in volts) between two ends of a wire made from one of these materials triples. A given piece of material’s resistance, measured in ohms, is equal to the quotient V/I for that piece of material.

Essential Components of Ohm’s Law

a)Current 

In electrical engineering, the current is the flow of electrically charged particles through a conducting medium, including electrons, protons, and ions. In standard international units of current, the current unit is the ampere, which is represented by the symbol ‘A.” It is necessary to measure the amount of electric current flowing through a circuit in coulombs per second. Thus, one ampere is equivalent to one coulomb of charge per second or 6.2 x 1018 electrons per second, which is the unit of measurement for current.

b)Voltage

Electrical pressure produced at two points of an electrical circuit that allows electric current to circulate across the circuit may be characterized as voltage. Voltage is measured in millivolts. So the difference in charge between two locations on a circuit may be thought of as the voltage, or vice versa. In honor of Italian physicist Alessandro Volta, the SI unit of voltage is called Volt, denoted by the letter “V.”

c)Resistance

Resistance may be described as the hurdles or hindrances that electrons encounter as they go through a circuit in its simplest form. Resistance is measured in ohms, which is denoted by the symbol in the SI. But the level of resistance provided by different items might change depending on the material from which they are constructed and their size. Metals, for example, have low resistivity, but materials such as plastics and rubbers have substantial resistance to electric current flow. Objects are categorized into three classes depending on their resistance power: insulators, conductors, and semiconductors. Insulators are the least resistive of the three types.

What does Ohm’s Law state, and how does it work?

This law states that if the potential difference between two points on a conductor is “V” and the current flowing through it is “I,” and other circumstances such as temperature stay constant, then at that point, we have – according to Ohm’s law.

V ∝ I

Alternatively, it may be written as

V = RI

Where R is the constant of proportionality called resistance

In what ways does Ohm’s Law have limitations?

It is stated in Ohm’s law that the electric current is proportional to the voltage and that the electric current is inversely proportional to the resistance. However, in the case of some materials, Ohm’s law does not hold.

Drawbacks or Limitations of Ohm’s law

Ohm’s rule does not apply to unilateral electrical elements like diodes and transistors since they only allow current to flow in one way.

Voltage and current will not be constant concerning time for non-linear electrical components having properties such as capacitance, making it impossible to apply Ohm’s law to them.

In the following sections, you will find examples of situations where Ohm’s law does not apply:

• An illustration of Ohm’s law’s limits is the diode, which may be used to comprehend it better. A voltage vs. current graph for a diode reveals that the relationship between voltage and current is not linear, as previously stated. Whenever the voltage is designated in the opposite direction of the current, the magnitude of the current remains constant. This shows that the current is created in the opposite direction and is different from the previous example.
• Let’s say you have a water volt-amp meter on hand. In this case, it is an example of a unilateral network, and Ohm’s law does not apply.
• It is also not required that all conductors follow Ohm’s law effectively. Silicon and germanium are examples of semiconductors that do not obey Ohm’s law and are referred to as Non-Ohmic conductors.

Type of materials according to Ohm’s Law

Materials with an Ohmic Response

Ohm’s law is not considered to be a fundamental rule. Ohm’s law may be applied to various conductors, a general rule. These sorts of conducting materials are called ohmic materials in the scientific community. Metals and alloys are examples of ohmic materials. 

Materials that are not ohmic

Ohm’s law does not apply to many essential conducting materials and technologies, a significant limitation. Non-ohmic conductors are considered one of the boundaries of Ohm’s law. Vacuum tubes, crystal rectifiers, thermistors, and transistors are examples of non-ohmic materials used in electronic devices. 

Power Calculation Using Ohm’s Law

Understanding Ohm’s law will aid in calculating the value of electric power. Check out the following formula for calculating power:

When the voltage and current values are known, P = V I

Current may be calculated using the following formula if power and voltage are known:

I = P/V

If power and current are known, use the following formula to compute voltage:

V = P/ I

Points to remember about limitations of Ohm’s Law

• Resistance, voltage, and current are all related according to Ohm’s law, which may be found here.
• However, it is not required for all devices to operate under Ohm’s law to function. Various non-ohmic gadgets are in use today.
• Ohm’s law asserts that the current is proportional to the voltage in a direct and unbroken relationship.
• Additionally, Ohm’s Law has other limits.
• In the event of nonmetallic conductors, Ohm’s Law will not apply.
• In the event of intricate circuits, the application of Ohm’s law might be challenging.

Conclusion

Individual networks are exempt from this provision. When the current flows in one direction, this is known as a bilateral network. Diodes, transistors, and other similar components make up this sort of network.

Also, Ohm’s law does not apply to non-linear components, as previously stated. Those components that do not have a perfect proportional relationship between current and applied voltage are non-linear elements. This implies that the resistance value of those elements varies depending on the applied voltage and current. The thyristor is an example of a non-linear element.