Bihar Police Constable Model Paper 1

Ohm’s law: Ohm’s law states that at a constant temperature, the current through a conductor between two points is directly proportional to the voltage across the two points.
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.
It helps to calculate the power, efficiency, current, voltage, and resistance of an element of an electrical circuit.
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 networks consist of 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. An example of a non-linear element is thyristor.
Ohm’s law is also not applicable to vacuum tubes.