- 1(current)
Q. No.The resistance of a wire is \(R\) ohm. If it is melted and stretched to \(n\) times its original length, its new resistance will be:
| 1. | \(nR\) | 2. | \(\frac{R}{n}\) |
| 3. | \(n^2R\) | 4. | \(\frac{R}{n^2}\) |
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Two solid conductors are made up of the same material and have the same length and the same resistance. One of them has a circular cross-section of area \( 𝐴 _1\) and the other one has a square cross-section of area \(A_2.\) The ratio of \(𝐴 _1 / 𝐴 _2 \) is:
1. \(1.5\)
2. \(1\)
3. \(0.8\)
4. \(2\)
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1. \(4~\Omega\)
2. \(8~\Omega\)
3. \(16~\Omega\)
4. \(2~\Omega\)
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The specific resistance of a conductor increases with:
| 1. | increase in temperature. |
| 2. | increase in cross-section area. |
| 3. | increase in cross-section and decrease in length. |
| 4. | decrease in cross-section area. |
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The dependence of resistivity \((\rho)\) on the temperature \((T)\) of a semiconductor is, roughly, represented by:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
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Two metal wires of identical dimensions are connected in series. If \(\sigma_1~\text{and}~\sigma_2\)
1. \(\dfrac{2\sigma_1 \sigma_2}{\sigma_1+\sigma_2}\)
2. \(\dfrac{\sigma_1 +\sigma_2}{2\sigma_1\sigma_2}\)
3. \(\dfrac{\sigma_1 +\sigma_2}{\sigma_1\sigma_2}\)
4. \(\dfrac{\sigma_1 \sigma_2}{\sigma_1+\sigma_2}\)
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Variation of current passing through a conductor with the voltage applied across its ends varies is shown in the diagram below. If the resistance \((R)\) is determined at points \(A\), \(B\), \(C\) and \(D\), we will find that:
| 1. | \(R_C = R_D\) | 2. | \(R_B>R_A\) |
| 3. | \(R_C>R_B\) | 4. | None of these |
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- 1(current)
Q. No.
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