Ohm's Law

Statement of Ohm’s Law

• The current flowing through metallic conductor is directly proportional to potential difference across it, provided that the temperature and other physical conditions remains same. 
• If I is current passes through a conductor and V is potential difference across its terminal, according to ohm’s law

       I α V (constant temperature)

                     OR

       V α I

       (V / I) = Constant

        V = IR

       Where R = Constant, it is called as resistance at given temperature

Resistance

• It is a property of conductor to oppose the flow of current through it. 
• The SI unit of resistance is ohm.
• One ohm = One volt / One ampere

According to ohm’s law

V = IR

I = V / R

Therefore, we can say that

I α V …… (1)

and I α (1 / R) …… (2)

• The current passes through conductor is directly proportional to potential difference across it. 
• The current passes through conductor is inversely proportional to resistance of metallic conductor.

Limitation of Ohm’s law

• The ohm’s law is not applicable for non – linear device such as semiconductor material.
• Not applicable for unilateral devices such as PN junction diodes and transistors.
• Th ohm’s law is not applicable for non – metallic conductors.

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