Ohm's Law Basics

Ohm's law describes the relationship between voltage ($V$), current ($I$), and resistance ($R$) in an electrical circuit. It states that the current through a conductor is directly proportional to the voltage across it, provided the temperature and other physical conditions remain constant.

Mathematically, this is expressed as:

\( V \propto I \)

Or,

\( V = IR \)

Where \( R \) (resistance) is constant.

Temperature Effects on Resistance

The resistance of most metallic conductors is not constant but varies with temperature. Typically, for metals, resistance increases as temperature increases.

Reasoning for Ohm's Law Violation

Ohm's law requires the resistance ($R$) to remain constant. If the temperature of the conductor increases:

• The resistance ($R$) of the conductor generally increases.
• This change in resistance means the linear relationship between voltage and current ($V \propto I$) is no longer maintained with a constant $R$.
• Therefore, Ohm's law may NOT hold true when the temperature of the conductor increases.

Analysis of Options

• Option 1 (Constant Temperature): This is a condition where Ohm's law *does* hold true.
• Option 2 (Linear V-I Relation): This is the definition of Ohm's law; if it holds, Ohm's law is satisfied.
• Option 3 (Temperature Increases): As explained above, increased temperature changes resistance, potentially violating Ohm's law.
• Option 4 (Metallic Conductor): Metallic conductors usually follow Ohm's law, but *only* if the temperature remains constant. The material type alone doesn't guarantee violation; the changing temperature does.