Ohm’s law states that the voltage or potential difference between two points is directly proportional to the current or electricity passing through the resistance, and directly proportional to the resistance of the circuit. The formula for Ohm’s law is V=IR. This relationship between current, voltage, and relationship was discovered by German scientist Georg Simon Ohm. Let us learn more about Ohms Law, Resistance, and its applications.
Ohm’s Law Definition
Most basic components of electricity are voltage, current, and resistance. Ohm’s law shows a simple relation between these three quantities. Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
Ohm’s Law Formula
Voltage= Current× Resistance
V= I×R
V= voltage, I= current and R= resistance
The SI unit of resistance is ohms and is denoted by Ω
This law is one of the most basic laws of electricity. It helps to calculate the power, efficiency, current, voltage, and resistance of an element of an electrical circuit.
Applications of Ohm’s Law
Ohm’s law helps us in determining either voltage, current or impedance or resistance of a linear electric circuit when the other two quantities are known to us. It also makes power calculation simpler.
How do we establish the current-voltage relationship?
In order to establish the current-voltage relationship, the ratio V / I remains constant for a given resistance, therefore a graph between the potential difference (V) and the current (I) must be a straight line.
How do we find the unknown values of resistance?
It is the constant ratio that gives the unknown values of resistance,
For a wire of uniform cross-section, the resistance depends on the length l and the area of cross-section A. It also depends on the temperature of the conductor. At a given temperature the resistance,
where ρ is the specific resistance or resistivity and is characteristic of the material of wire. The specific resistance or resistivity of the material of the wire is,
If ‘r’ is the radius of the wire, then the cross-sectional area, A = πr². Then the specific resistance or resistivity of the material of the wire is,
Limitations of ohms law
Ohm’s law is not applicable to unilateral networks. Unilateral networks allow the current to flow in one direction. Such types of network consist elements like a diode, transistor, etc.
Ohm’s law is also not applicable to non – linear elements. Non-linear elements are those which do not have current exactly proportional to the applied voltage that means the resistance value of those elements changes for different values of voltage and current. Examples of non – linear elements are the thyristor.