Which of the following statements are correct about resistance?A. Resi...
Resistance (R) of a conductor at a given temperature:
- is directly proportional to the length (l)
- is inversely proportional to the area of cross-section (a)
- depends on the nature of the material (ρ)
R=ρ×l/a
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Which of the following statements are correct about resistance?A. Resi...
Resistance of a conductor:
The resistance of a conductor refers to the opposition it offers to the flow of electric current. It depends on various factors, including the length, cross-sectional area, and nature of the material.
Statement A: Resistance of a conductor is directly proportional to the length.
This statement is correct. The resistance of a conductor is directly proportional to its length. This means that as the length of a conductor increases, its resistance also increases. This relationship can be explained by the fact that a longer conductor provides more pathway for the current to travel through, resulting in a higher resistance.
Statement B: Resistance of a conductor is directly proportional to the area of cross-section.
This statement is incorrect. The resistance of a conductor is actually inversely proportional to its cross-sectional area. In other words, as the cross-sectional area of a conductor increases, its resistance decreases. This relationship can be understood by considering that a larger cross-sectional area allows more space for the current to flow through, resulting in a lower resistance.
Statement C: Resistance of a conductor depends on the nature of the material.
This statement is correct. The resistance of a conductor is influenced by the nature of the material it is made of. Different materials have different resistivities, which is a measure of how strongly they resist the flow of electric current. For example, materials like copper and aluminum have low resistivities and thus offer lower resistance, while materials like rubber and glass have high resistivities and offer higher resistance.
Statement D: Resistance of conductor is inversely proportional to the length.
This statement is incorrect. As mentioned earlier, the resistance of a conductor is directly proportional to its length, not inversely proportional. As the length of a conductor increases, its resistance also increases.
Therefore, the correct statements about resistance are:
- Resistance of a conductor is directly proportional to the length.
- Resistance of a conductor depends on the nature of the material.
Hence, option 'B' is the correct answer.
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