Before heading over to understanding the formula for electric resistance, let us try to understand the meaning of electric resistance and what exactly is its essence in a circuit. So electrical resistance is the opposite or the resistance offered by a circuit to free passage of current. Resistance exacts like friction in a circuit. Like friction opposes the free and easy motion, electrical resistance resists the flow of current through a wire.
Formula for Electric Resistance
There are basically two methods of finding the electrical resistance of a circuit. One is the conventional formula for electric resistance.
R= pl/A
In the formula given above, p is rho which signifies the resistivity of a material. L is the length of the conductor given to you and a is the area of the cross-section of the wire or conductor given to you. This is the basic formula to find the electrical resistance of any given conductor.
Another formula using which you can determine the electrical resistance of a given system is by using Ohm’s law. Ohm’s law is one of the most famous practical laws of circuital physics. Ohm’s law states that the current flowing through a circuit is directly proportional to the voltage applied across it and inversely proportional to the resistance offered by the wire, provided that the temperature remains constant. The formula for ohm’s law is
V= IR
Here V signifies the applied voltage
I represents the current
R is the electrical resistance
From the formula given above, we can find the electrical resistance if the voltage and the current are known to us.