Ohm’s Law

Ohm’s law states that so long as the physical state of a conductor remains the same, the potential difference (V) applied between the ends of the conductor bears a constant ratio to the electric current(I) passing through it.

In simple words this means, that the ratio of potential difference (V) across the conductor and the current flowing through the conductor will remain constant when physical state of the conductor will remain constant (i.e. temperature, length, cross sectional area etc.) therefore V/I = Constant and this constant is called as resistance which is denoted by R therefore,  V/I = R

If, for example, the current (I) is unknown but the voltage (E) and resistance (R) are known,
Where,

I = Current in amperes (A)

E = Electromotive force (EMF) in volts (V) R = Resistance in ohms (Ω)


Then, V = I x R, I = V/R and R=V/I

Example

If battery EMF is 12.8 volts and supplies a current of 3.2 A, then what is the resistance of the circuit? According to Ohm’s law,