Q. No.The solids which have the negative temperature coefficient of resistance are:
1.
insulators only
2.
semiconductors only
3.
insulators and semiconductors
4.
metals
For transistor action, which of the following statements is correct?
| 1. | Base, emitter, and collector regions should have the same size. |
| 2. | Both emitter junction, as well as the collector junction, are forward biased. |
| 3. | The base region must be very thin and lightly doped. |
| 4. | Base, emitter, and collector regions should have the same doping concentrations. |
The increase in the width of the depletion region in a \(\mathrm{p\text{-}n}\) junction diode is due to:
| 1. | reverse bias only |
| 2. | both forward bias and reverse bias |
| 3. | increase in forwarding current |
| 4. | forward bias only |
For the logic circuit shown, the truth table is:
| 1. |
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| 2. |
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| 3. |
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| 4. |
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Carbon, silicon, and germanium have four valence electrons each. These are characterized by valence and conduction bands separated by the energy bandgap respectively equal to \((E_g)_C, (E_g)_{Si}~\text{and}~(E_g)_{Ge}\). Which of the following statements is true?
| 1. | \((E_g)_{Si} < (E_g)_{Ge}<(E_g)_{C}\) |
| 2. | \((E_g)_{C} < (E_g)_{Ge}>(E_g)_{Si}\) |
| 3. | \((E_g)_{C} > (E_g)_{Si}>(E_g)_{Ge}\) |
| 4. | \((E_g)_{C} =(E_g)_{Si}=(E_g)_{Ge}\) |
In an unbiased p-n junction, holes diffuse from the p-region to n-region because :
| 1. | free electrons in the n-region attract them. |
| 2. | they move across the junction by the potential difference. |
| 3. | hole concentration in p-region is more as compared to n-region. |
| 4. | All the above. |
When a forward bias is applied to a p-n junction, it
1. raises the potential barrier.
2. reduces the majority carrier current to zero.
3. lowers the potential barrier.
4. None of the above.
For a transistor amplifier, the voltage gain:
| 1. | remains constant for all frequencies. |
| 2. | is high at high and low frequencies and constant in the middle-frequency range. |
| 3. | is low at high and low frequencies and constant at mid frequencies. |
| 4. | none of the above. |
In a half-wave rectification, what is the output frequency if the input frequency is \(50\) Hz?
| 1. | \(50~\text{Hz}\) | 2. | \(100~\text{Hz}\) |
| 3. | \(25~\text{Hz}\) | 4. | \(60~\text{Hz}\) |
For a CE-transistor amplifier, the audio signal voltage across the collector resistance of \(2\) k\(\Omega\) is \(2\) V. Suppose the current amplification factor of the transistor is \(100.\) What is the base current if the base resistance is \(1\) k\(\Omega?\)
1. \(14\) \(\mu\)A
2. \(12\) \(\mu\)A
3. \(15\) \(\mu\)A
4. \(10\) \(\mu\)A
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