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. \(1.6 \times 10^{-5}~\Omega\text-\text{m}\)
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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 of radius \(0.5\) mm and conductivity \(5\times 10^7\) S/m is subjected to an electric field of \(10\) mV/m. The expected value of current in the wire will be:
1. \(125\pi ~\mathrm{mA}\)
2. \(250\pi ~\mathrm{mA}\)
3. \(325\pi ~\mathrm{mA}\)
4. \(420\pi ~\mathrm{mA}\)
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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