Q. No.\(\mathrm{C},\) \(\mathrm{Si},\) 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). |
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. |
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. \(4\times10^7~\Omega~\)
1. \(2~\text{mA}\)
2. \(4~\text{mA}\)
3. \(6~\text{mA}\)
4. \(8~\text{mA}\)
In a semiconductor;
| (A) | there are no free electrons at \(0^\circ\text{K}.\) |
| (B) | there are no free electrons at any temperature. |
| (C) | the number of free electrons increases with temperature. |
| (D) | the number of free electrons is less than that in a conductor. |
Choose the correct option from the given ones:
| 1. | (A) and (B) only |
| 2. | (B) and (C) only |
| 3. | (A), (C), and (D) only |
| 4. | (A), (B), and (D) only |
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. \(n_{p}\neq n_{e}\)
| Assertion (A): | The value of current through \(\mathrm{p\text-n}\) junction in the given figure will be \(10~\text{mA}.\) |
| Reason (R): | In the above figure, \(\mathrm{p\text-}\)side is at a higher potential than \(\mathrm{n\text-}\)side. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
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. \(100~\text{Hz}\)
(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. | \(4.5\times10^{9}~\text{m}^{-3}, 4.5\times 10^{9}~\text{m}^{-3}\) |
| 1. | metals |
| 2. | intrinsic semiconductors |
| 3. | \(\mathrm{p} \text-\)type extrinsic semiconductors |
| 4. | \(\mathrm{n} \text-\)type extrinsic semiconductors |
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