The correct option is A straight line passing through the origin.
Explanation
The relationship between electric current and potential difference in a conductor is governed by Ohm’s Law. This law states that the current ($I$) flowing through a conductor is directly proportional to the potential difference ($V$) applied across its ends, provided that physical conditions, particularly temperature, remain constant.
Detailed Analysis:
- Mathematically, Ohm's Law is expressed as $V \propto I$ or $V = IR$, where $R$ is the resistance of the conductor.
- This relationship corresponds to the linear equation $y = mx$, where $y$ represents voltage, $x$ represents current, and $m$ represents the constant of proportionality (resistance).
- Because the relationship is linear and there is no intercept term (i.e., when $I=0$, $V=0$), the graphical representation of Current ($I$) versus Voltage ($V$) for an ohmic conductor is a straight line passing through the origin.
- Conductors that follow this linear behavior are called ohmic conductors (e.g., pure metals like copper and aluminum). Conductors that produce non-linear graphs (curves) are termed non-ohmic conductors (e.g., diodes, electrolytes).
Key Takeaway: For an ohmic conductor at a constant temperature, the ratio $V/I$ is constant, resulting in a linear I-V characteristic curve that passes through the origin.