Resistance of a conductor depends on:
a) length
b) length, area of cross-section, nature of material, temperature of conductor
c) length and area of cross-section
d) length, area of cross-section, nature of material

The correct answer is option 'B', which states that the resistance of a conductor depends on the length, area of cross-section, nature of material, and temperature of the conductor. Let's explore each of these factors in detail:

1. Length:
The resistance of a conductor is directly proportional to its length. This means that the longer the conductor, the higher its resistance. This can be understood by considering that as the length of the conductor increases, the number of collisions between the electrons and the atoms in the material also increases, leading to a higher resistance.

2. Area of Cross-Section:
The resistance of a conductor is inversely proportional to the area of its cross-section. This means that the larger the cross-sectional area of the conductor, the lower its resistance. A larger cross-sectional area allows more space for the flow of electrons, reducing the number of collisions and hence the resistance.

3. Nature of Material:
The resistance of a conductor also depends on the nature of the material it is made of. Different materials have different resistivities, which is a measure of how strongly a material opposes the flow of electric current. Materials with higher resistivities have higher resistance, while materials with lower resistivities have lower resistance.

4. Temperature of Conductor:
The resistance of most conductors increases with an increase in temperature. This is because as the temperature rises, the atoms in the material vibrate more vigorously, leading to an increased number of collisions with the flowing electrons. This higher collision rate results in an increased resistance.

Overall, the resistance of a conductor depends on multiple factors including length, area of cross-section, nature of material, and temperature. Understanding these factors is crucial in designing and analyzing electrical circuits and systems.