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). |
(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. | \(4.5\times10^{9}~\text{m}^{-3}, 4.5\times 10^{9}~\text{m}^{-3}\) |
Why can't we take one slab of p-type semiconductor and physically join it to another slab of n-type semiconductor to get a p-n junction?
| 1. | the diffusion of majority charge carriers will not occur. |
| 2. | the junction will behave as a discontinuity for the flowing charge carriers. |
| 3. | the junction will behave as a continuity for the flowing charge carriers. |
| 4. | both (1) and (2). |
The \(V\text-I\) characteristic of a silicon diode is shown in the figure. The resistance of the diode at \(I_D = 15~\text{mA}\) is:
1. \(20~\Omega\)
2. \(30~\Omega\)
3. \(15~\Omega\)
4. \(10~\Omega\)
The \((V\text-I)\) characteristic of a silicon diode is shown in the figure. The resistance of the diode at \(V_D=-10\) V is:
1. \(1\times10^7~\Omega~\)
2. \(2\times10^7~\Omega~\)
3. \(3\times10^7~\Omega~\)
4. \(4\times10^7~\Omega~\)
1. less than \(100~\Omega\)
2. zero
3. infinite
4. \(150~\Omega\)
Which one of the following is not true for the photodiodes?
| 1. | The current in the forward bias is more than the current in the reverse bias. |
| 2. | Photodiodes are preferably used in the reverse bias condition for measuring light intensity. |
| 3. | Photodiodes are preferably used in the forward bias condition for measuring light intensity |
| 4. | In photodiodes, only a small portion of the incident photons gets converted to electric current. |
Which material is preferred for solar cells?
1. \(\text{Si}\)
2. \(\text{GaAs}\)
3. \(\text{CdS}\)
4. both \(\text{Si}\) and \(\text{GaAs}\)
The output waveform (Y) of the AND gate for the following inputs A and B given in the figure is:
| 1. |  |
| 2. |  |
| 3. |  |
| 4. | None of these |
The output waveform (\(\text{Y}\)) of the \(\mathrm{OR}\) gate for the following inputs \(\mathrm{A}\) and\(\mathrm{B}\) given in the figure is:
| 1. | |
| 2. | |
| 3. | |
| 4. | none of these |
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