Q. No.If a full-wave rectifier circuit is operating from \(50~\text{Hz}\) mains, the fundamental frequency in the ripple will be:
1. \(25~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(70.7~\text{Hz}\)
4. \(100~\text{Hz}\)
1. \(25~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(70.7~\text{Hz}\)
4. \(100~\text{Hz}\)
The barrier potential of a \(\mathrm{p\text-n}\) junction diode does not depend on:
| 1. | diode design | 2. | temperature |
| 3. | forward bias | 4. | doping density |
\(\mathrm{C},\) \(\mathrm{Si},\) and \(\mathrm{Ge}\) have the same lattice structure. Why is the \(\mathrm{C}\) insulator?
| 1. | because ionization energy for \(\mathrm{C}\) is the least in comparison to \(\mathrm{Si}\) and \(\mathrm{Ge}\). |
| 2. | because ionization energy for \(\mathrm{C}\) is highest in comparison to \(\mathrm{Si}\) and \(\mathrm{Ge}\). |
| 3. | the number of free electrons for conduction in \(\mathrm{Ge}\) and \(\mathrm{Si}\) is significant but negligibly small for \(\mathrm{C}\). |
| 4. | both (2) and (3). |
(given: \(n_i=1.5\times10^{16}~\text{m}^{-3}\))
| 1. | \(5\times10^{22}~\text{m}^{-3}, 4.5\times10^{9}~\text{m}^{-3}\) |
| 2. | \(4.5\times10^{9}~\text{m}^{-3}, 5\times 10^{22}~\text{m}^{-3}\) |
| 3. | \(5\times10^{22}~\text{m}^{-3}, 5\times10^{22}~\text{m}^{-3}\) |
| 4. | \(4.5\times10^{9}~\text{m}^{-3}, 4.5\times 10^{9}~\text{m}^{-3}\) |
The \((V\text-I)\) characteristic of a silicon diode is shown in the figure. The resistance of the diode at \(V_D=-10~\text V\) is:
1. \(1\times10^7~\Omega~\)
2. \(2\times10^7~\Omega~\)
3. \(3\times10^7~\Omega~\)
4. \(4\times10^7~\Omega~\)
For the given circuit of the \(\mathrm{p\text-n}\) junction diode, which of the following statements is correct?
| 1. | In F.B. the voltage across \(R\) is \(V.\) |
| 2. | In R.B. the voltage across \(R\) is \(V.\) |
| 3. | In F.B. the voltage across \(R\) is \(2V.\) |
| 4. | In R.B. the voltage across \(R\) is \(2V.\) |
| Statement A: | A Zener diode is connected in reverse bias when used as a voltage regulator. |
| Statement B: | The potential barrier of \(\mathrm{p\text-n}\) junction lies between \(0.2\) V to \(0.3\) V. |
| 1. | Statement A is correct and Statement B is incorrect. |
| 2. | Statement A is incorrect and Statement B is correct. |
| 3. | Statement A and Statement B both are correct. |
| 4. | Statement A and Statement B both are incorrect. |
| 1. | The resistivity of a semiconductor increases with an increase in temperature. |
| 2. | Substances with an energy gap of the order of \(10~\text{eV}\) are insulators. |
| 3. | In conductors, the valence and conduction bands may overlap. |
| 4. | The conductivity of a semiconductor increases with an increase in temperature. |
An electric field is applied to a semiconductor. Let the number of charge carriers be \(n\) and the average drift speed be \(v.\) If the temperature is increased, then:
| 1. | both \(n\) and \(v\) will increase. |
| 2. | \(n\) will increase but \(v\) will decrease. |
| 3. | \(v\) will increase but \(n\) will decrease. |
| 4. | both \(n\) and \(v\) will decrease. |
Let \(n_{p}\) and \(n_{e}\) be the number of holes and conduction electrons in an intrinsic semiconductor. Then:
1. \(n_{p}> n_{e}\)
2. \(n_{p}= n_{e}\)
3. \(n_{p}< n_{e}\)
4. \(n_{p}\neq n_{e}\)
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