Question

The resistance of a conductor is directly proportional to its

• A. Area of cross-section
• B. Density
• C. Melting point
• D. Length

Answer 1

The correct option is D

Length

Explanation of the correct option:

1. Resistance of a material is defined as the property of a material by virtue of which it opposes the flow of electric current.
2. Formula: Resistance $R$ is given by $R=\frac{\rho l}{A}$, where $\rho$ is the resistivity, $l$ is the length, and $A$ is the area of the cross-section.
3. In the case of option D, we can see from the formula that the resistance of a conductor is directly proportional to the length of the conductor.

Explanation of the incorrect options:

1. In the case of option A, the resistance of a conductor is inversely proportional to the area of the cross-section of the conductor.
2. In the case of option B, the resistance of a conductor is independent of the density of the conductor.
3. In the case of option C, the resistance of a conductor is independent of the melting point of the conductor.

Hence, option D is the correct answer.