Q. No.When \(5~\text{V}\) potential difference is applied across a wire of length \(0.1~\text{m}\), the drift speed of electrons is \(2.5\times 10^{-4}~\text{ms}^{-1}\). If the electron density in the wire is \(8\times 10^{28}~\text{m}^{-3}\), the resistivity of the material is close to:
1. \(1.6 \times 10^{-8}~\Omega\text-\text{m}\)
2. \(1.6 \times 10^{-7}~\Omega\text-\text{m}\)
3. \(1.6 \times 10^{-6}~\Omega\text-\text{m}\)
4. \(1.6 \times 10^{-5}~\Omega\text-\text{m}\)
| 1. |  |
3. |  |
| 2. |  |
4. |  |
1. \(0.02\)
2. \(3\)
3. \(2\)
4. \(0.2\)
1. \(2~\Omega \text{m}\)
2. \(4~\Omega \text{m}\)
3. \(0.4~\Omega \text{m}\)
4. \(0.2~\Omega \text{m}\)
A current through a wire depends on time as \(i=\alpha_0t+\beta t^2\) where \(\alpha_0=20~\mathrm{A/s}\) and \(\beta =8~\mathrm{As^{-2}}\). The charge crossed through a cross-section of wire in \(15~\mathrm{s}\) is:
1. \(2250~\mathrm{C}\)
2. \(11250~\mathrm{C}\)
3. \(2100~\mathrm{C}\)
4. \(260~\mathrm{C}\)
A cylindrical wire with a radius of \(0.5\text{ mm}\) and electrical conductivity of \(5\times 10^7\text{ S/m} \) is subjected to a uniform electric field of \(10\text{ milivolts per meter}.\) What is the expected current flowing through the wire?
| 1. | \(125\pi ~\text{mA}\) | 2. | \(250\pi ~\text{mA}\) |
| 3. | \(325\pi ~\text{mA}\) | 4. | \(420\pi ~\text{mA}\) |
1. \(16\pi~\text{A}\)
2. \(64\pi~\text{A}\)
3. \(32\pi~\text{A}\)
4. \(48\pi~\text{A}\)
1. \(10\)
2. \(14\)
3. \(16\)
4. \(12\)
\(1.7\times10^{-8}~\Omega\) m, the force experienced by a moving electron in the wire is:
(charge on electron = \(1.6\times 10^{-19}\) C)
1. \(112\times 10^{-23}\) N
2. \(240\times10^{-23}\) N
3. \(136\times 10^{-23}\) N
4. \(321\times 10^{-23}\) N
\(A:\) cross-sectional area of the conductor
\(q:\) charge on each charge carrier
\(I:\) current through the conductor
Then the expression of drift velocity is:
1. \(\frac{nAq}{I}\)
2. \(\frac{I}{nAq}\)
3. \({nAqI}\)
4. \(\frac{IA}{nq}\)
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