Q. No.When a \(\mathrm{p\text-n}\) junction is forward biased, then:
1.
the depletion region becomes thick.
2.
the \(\mathrm{p}\text-\)side is at a higher potential than \(\mathrm{n\text-}\)side.
3.
the current flowing is zero.
4.
the effective resistance is of the order of \(10^6 ~\Omega\).
A semiconductor is known to have an electron concentration of \(8\times 10^{13}~\text{cm}^{-3},\) and a hole concentration of \(5\times 10^{2}~\text{cm}^{-3}.\) The semiconductor is:
| 1. | \(\mathrm{n}\text-\)type | 2. | \(\mathrm{p}\text-\)type |
| 3. | intrinsic | 4. | insulator |
Carbon, Silicon, and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy gaps represented by \(\left(E_g\right)_C,(E_g)_{Si}~\text{and}~(E_g)_{Ge}\) respectively. Which one of the following relationships is true in their case?
1. \(\left(E_g\right)_C<\left(E_g\right)_{G e} \)
2. \(\left(E_g\right)_C>\left(E_g\right)_{S i} \)
3. \(\left(E_g\right)_C=\left(E_g\right)_{S i} \)
4. \(\left(E_g\right)_C<\left(E_g\right)_{S i}\)
If a small amount of aluminium is added to the silicon crystal:
| 1. | its resistance decreases. |
| 2. | it becomes a \(\mathrm{p\text-}\)type semiconductor. |
| 3. | there will be fewer free electrons than holes in the semiconductor. |
| 4. | All of these are correct. |
In the given figure, the potential difference between \(A\) and \(B\) is:
| 1. | \(0\) | 2. | \(5\) volt |
| 3. | \(10\) volt | 4. | \(15\) volt |
In a common-emitter transistor amplifier, the audio signal voltage across the collector is 3 V. The resistance of the collector is 3 k. If the current gain is 100 and the base resistance is 2 k, the voltage and power gain of the amplifier are:
1. 200 and 1000
2. 15 and 200
3. 150 and 15000
4. 20 and 2000
If in a \(\mathrm{p\text-n}\) junction, a square input signal of \(10\) V is applied as shown, then the output across \(R_L\) will be:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
The given graph represents the \(V\text-I\) characteristics of a semiconductor device. Which of the following statements is correct?
| 1. | It is a \(V\text-I\) characteristic of a solar cell where the point \(A\) represents open-circuit voltage and the point \(B\) represents short-circuit current. |
| 2. | It is for a solar cell and points \(A\) and \(B\) represents open-circuit voltage and current respectively. |
| 3. | It is for a photodiode and points \(A\) and \(B\) represents open-circuit voltage and current respectively. |
| 4. | It is for an LED and points \(A\) and \(B\) represents open-circuit voltage and short-circuit current respectively. |
Transfer characteristic [output voltage vs input voltage ] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used:
1. in region III
2. both in region (I) and (III)
3. in region II
4. in region I
| 1. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=5\times10^{22}~\text{m}^{-3}\) |
| 2. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=2.5\times10^{23}~\text{m}^{-3}\) |
| 3. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=2.5\times10^{10}~\text{m}^{-3}\) |
| 4. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=5\times10^{9}~\text{m}^{-3}\) |
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