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Q. No.The dynamic resistance of a diode is given by; \(R=\dfrac{26}{i(\text{mA})}~\Omega,\) where \(i\) is the diode current.
Statement I:
If the current through the diode increases, then the dynamic resistance decreases.
Statement II:
If the temperature of the diode is increased, with the potential difference fixed, the dynamic resistance decreases.
1.
Statement I is incorrect and Statement II is correct.
2.
Both Statement I and Statement II are correct.
3.
Both Statement I and Statement II are incorrect.
4.
Statement I is correct and Statement II is incorrect.
Subtopic: Â PN junction |
 73%
Level 2: 60%+
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Potential barrier across a \(\mathrm{p\text-n}\) junction is \(0.6\) V. Electric field intensity, in the depletion region having a width of \(6\times10^{-6}\) m, will be:
1. \(1\times10^{5}\) N/C
2. \(2\times10^{5}\) N/C
3. \(3\times10^{5}\) N/C
4. \(4\times10^{5}\) N/C
1. \(1\times10^{5}\) N/C
2. \(2\times10^{5}\) N/C
3. \(3\times10^{5}\) N/C
4. \(4\times10^{5}\) N/C
Subtopic: Â PN junction |
 93%
Level 1: 80%+
JEE
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An intrinsic Germanium \(\mathrm{(Ge)}\) semiconductor having \(2.5 \times 10^{29}\) atoms per \(\text m^3\) is doped uniformly by trivalent aluminium at \(1~\text{ppm}.\)If the thermally generated electron concentration at room temperature is \(n_i=10^{17}/\text m^3,\) the resulting electron concentration after doping at the same temperature will be:
1. \(2.5 \times 10^{29}~\text m^{-3}\)
2. \(4 \times 10^{10}~\text m^{-3}\)
3. \(2.5 \times 10^{18}~\text m^{-3}\)
4. \(4 \times 10^{20}~\text m^{-3}\)
1. \(2.5 \times 10^{29}~\text m^{-3}\)
2. \(4 \times 10^{10}~\text m^{-3}\)
3. \(2.5 \times 10^{18}~\text m^{-3}\)
4. \(4 \times 10^{20}~\text m^{-3}\)
Subtopic: Â Types of Semiconductors |
 73%
Level 2: 60%+
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A \(\mathrm{Ge}\) specimen is doped with \(\mathrm{Al}.\) The concentration of acceptor atoms is approximately \(10^{24}~\text{m}^{-3}.\) Given that intrinsic carrier concentration is nearly \(10^{19}~\text{m}^{-3},\) then the concentration of electrons in the specimen is nearly:
1. \(10^{10}~\text{m}^{-3}\)
2. \(10^{14}~\text{m}^{-3}\)
3. \(10^{19}~\text{m}^{-3}\)
4. \(10^{18}~\text{m}^{-3}\)
1. \(10^{10}~\text{m}^{-3}\)
2. \(10^{14}~\text{m}^{-3}\)
3. \(10^{19}~\text{m}^{-3}\)
4. \(10^{18}~\text{m}^{-3}\)
Subtopic: Â Types of Semiconductors |
 84%
Level 1: 80%+
Hints
The depletion width of a \(\mathrm{p\text-n}\) junction depends on which of the following parameters given below?
Choose the correct option from the given ones:
| (a) | temperature |
| (b) | type of semiconductor material |
| (c) | doping concentration |
| (d) | biasing of junction |
Choose the correct option from the given ones:
| 1. | (a), (b), (c) |
| 2. | (b), (c), (d) |
| 3. | (a), (c), (d) |
| 4. | (a), (b), (c), (d) |
Subtopic: Â PN junction |
 78%
Level 2: 60%+
Hints
Match the items in List-I with their corresponding descriptions in List-II:
Codes:
| List-I | List-II | ||
| (a) | Intrinsic semiconductor | (e) | Prepared by adding phosphorus |
| (b) | \(\mathrm{n}\text-\)type semiconductor | (f) | The width is nearly one micron |
| (c) | \(\mathrm{p}\text-\)type semiconductor | (g) | Silicon |
| (d) | Depletion layer | (h) | Prepared by adding indium |
Codes:
| 1. | (a)-(g), (b)-(e), (c)-(h), (d)-(f) |
| 2. | (a)-(h), (b)-(f), (c)-(e), (d)-(g) |
| 3. | (a)-(e), (b)-(g), (c)-(f), (d)-(h) |
| 4. | (a)-(f), (b)-(h), (c)-(g), (d)-(e) |
Subtopic: Â Types of Semiconductors |
 92%
Level 1: 80%+
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The energy band gap of semiconducting material to produce violet (wavelength \(=4000~\mathring{A}\)) LED is (nearly):
1. \(3~\text{eV}\)
2. \(5~\text{eV}\)
3. \(1~\text{eV}\)
4. \(7~\text{eV}\)
1. \(3~\text{eV}\)
2. \(5~\text{eV}\)
3. \(1~\text{eV}\)
4. \(7~\text{eV}\)
Subtopic: Â Energy Band theory |
 88%
Level 1: 80%+
JEE
Hints
The charge on a \(\mathrm{p}\)-type semiconductor is:
| 1. | neutral |
| 2. | negative |
| 3. | positive |
| 4. | may be positive or negative |
Subtopic: Â Types of Semiconductors |
 75%
Level 2: 60%+
Hints
What is responsible for the formation of the depletion layer across the \(\mathrm{p\text-n}\) junction?
| 1. | Drift of holes. |
| 2. | Drift of electrons. |
| 3. | Diffusion of holes and electrons. |
| 4. | Absence of diffusion of holes and electrons. |
Subtopic: Â PN junction |
 83%
Level 1: 80%+
Hints
A full wave rectifier circuit along with the input and output voltages is shown in the figure. The contribution to the output voltage from diode-\(2\) is:
| 1. | \(A,C\) | 2. | \(B,D\) |
| 3. | \(B,C\) | 4. | \(A,D\) |
Subtopic: Â Rectifier |
 82%
Level 1: 80%+
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