Which of the following statements are correct?
(A) Resistance is a property that resists the flow of electrons in a conductor.
(B) The resistance of a conductor depends on the material of the conductor.
(C) The resistance of a conductor depends inversely on its length.
(D) The resistance of a conductor depends inversely on its area of cross-section.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B) and (D) only
The resistance of a wire is given by \(R=\rho\displaystyle\frac{l}{A}\), where \(l\) is its length, \(A\) its area of cross-section and \(\rho\) the resistivity, a constant of the material.
(A) Resistance is a property that resists the flow of electrons in a conductor. Correct. Resistance is the property of a conductor that opposes the flow of charge (electrons) through it; it is measured in ohms.
(B) The resistance of a conductor depends on the material of the conductor. Correct. The material enters through \(\rho\): a copper wire has far less resistance than a nichrome wire of the same size.
(C) The resistance of a conductor depends inversely on its length. Incorrect. \(R\) is directly proportional to the length: doubling the length doubles the resistance.
(D) The resistance of a conductor depends inversely on its area of cross-section. Correct. \(A\) is in the denominator, so a thicker wire has less resistance.