
| 1. | length of the wire |
| 2. | area of cross-section of the conductor |
| 3. | nature of material and temperature across the conductor |
| 4. | All of these |
| Assertion (A): | The conductance of a wire increases linearly with its cross-sectional area, but is inversely proportional to its length. |
| Reason (R): | The conductance is inverse of the resistance \((R)\) and, \(R=\rho\dfrac lA,\) where \(l=\) length, \(A\) = area of cross-section. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| Assertion (A): | Alloys such as constantan and manganin are used in making standard resistance coils. |
| Reason (R): | Constantan and manganin have a very small value of temperature coefficient of resistance. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| 1. | \(1\times 10^{-6} ~\Omega-\text{m}\) |
| 2. | \(4\times 10^{-7}~\Omega-\text{m}\) |
| 3. | \(3\times 10^{-7}~\Omega-\text{m}\) |
| 4. | \(2\times 10^{-7}~\Omega-\text{m}\) |
A negligibly small current is passed through a wire of length \(15~\text{m}\) and uniform cross-section \(6.0\times10^{-7}~\text{m}^2,\) and its resistance is measured to be \(5.0~\Omega.\) What is the resistivity of the material at the temperature of the experiment?
| 1. | \(1\times 10^{-7}~\Omega\text{m}\) | 2. | \(2\times 10^{-7}~\Omega\text{m}\) |
| 3. | \(3\times 10^{-7}~\Omega\text{m}\) | 4. | \(1.6\times 10^{-7}~\Omega\text{m}\) |