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. | \(\frac{R}{n^2}\) |
| 1. | \(\dfrac {2.0 ~\times~10^{-3}}{\pi} ~\Omega\) | 2. | \(5.0 ~\times~10^{-13}\pi~\Omega\) |
| 3. | \(\dfrac {1.0}{2\pi}~\Omega\) | 4. | \(\dfrac{2.0}{\pi}~\Omega\) |
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. \(2\)
1. \(4~\Omega\)
2. \(8~\Omega\)
3. \(16~\Omega\)
4. \(2~\Omega\)
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. |
The plot of current \(I~\text{(A)}\) flowing through a metallic conductor versus the applied voltage \(V~\text{(volt)}\) across the ends of a conductor is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
1. \(T_{1}=T_{2}\)
2. \(T_{2}>T_{1}\)
3. \(T_{1}>T_{2}\)
4. Insufficient information to conclude.
The dependence of resistivity \((\rho)\) on the temperature \((T)\) of a semiconductor is, roughly, represented by:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
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. \(\dfrac{\sigma_1 \sigma_2}{\sigma_1+\sigma_2}\)
| 1. | directly proportional to \(b\) |
| 2. | inversely proportional to \(t\) |
| 3. | inversely proportional to \(L\) |
| 4. | both (1) and (2) |
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