In a good conductor, the energy gap between the conduction band and the valence band is
1. Infinite
2. Wide
3. Narrow
4. Zero
A Ge specimen is doped with Al. The concentration of acceptor atoms is . Given that the intrinsic concentration of electron hole pairs is , the concentration of electrons in the specimen is:
1. | \(10^{17} / \mathrm{m}^3 \) | 2. | \(10^{15} / \mathrm{m}^3 \) |
3. | \(10^4 / \mathrm{m}^3 \) | 4. | \(10^2 / \mathrm{m}^3\) |
In a semiconducting material, the mobilities of electrons and holes are and respectively. Which of the following is true?
1. \(\mu_{e} > \mu _{h}\)
2. \(\mu_{e} < \mu _{h}\)
3. \(\mu_{e} = \mu _{h}\)
4. \(\mu_{e} <0; ~\mu _{h}>0\)
The diode used in the circuit shown in the figure has a constant voltage drop of 0.5 V at all currents and a maximum power rating of 100 milliwatts. What should be the value of the resistor R, connected in series with the diode for obtaining maximum current?
1. 1.5
2. 5
3. 6.67
4. 200
The figure shows two NAND gates followed by a NOR gate. Which of the following logic gate does the figure represent?
1. OR
2. AND
3. NAND
4. None of these
The diagram of a logic circuit is given below. The output F of the circuit is represented by:
1. W(X+Y)
2. W.(X.Y)
3. W+(X.Y)
4. W+(X+Y)
How much is the forbidden gap (approximately) in the energy bands of germanium at room temperature?
1. \(1.1~\text{eV}\)
2. \(0.1~\text{eV}\)
3. \(0.67~\text{eV}\)
4. \(6.7~\text{eV}\)
Which of the following logic gate is a universal gate?
1. OR
2. NOT
3. AND
4. NOR
The correct symbol for zener diode is:
1. | 2. | ||
3. | 4. |
Two PN-junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be:
1. | In the circuit (1) and (2) |
2. | In the circuit (2) and (3) |
3. | In the circuit (1) and (3) |
4. | Only in the circuit (1) |