Physical Electronics, Electron Devices and ICs Question and Answers

Physical Electronics, Electron Devices and ICs Question and Answers

Q1. A Schottky diode clamp is used along with a switching BJT for

1. Reducing the power dissipation
2. Reducing the switching time
3. Increasing the value of beta
4. Reducing the base current

Answer : b

Q2. For an an-channel JFET, having drain source voltage constant if the gate source voltage is increased (more negative) pinch-off would occur for

1. High values of drain current
2. Saturation value of drain current
3. Zero drain current
4. Gate current equal to the drain current

Answer : c

Q3. Conversion efficiency of a silicon solar cell is about

5%

10%

14%

24%

Answer : c

Q4. A semiconductor photo-diode uses

Photo-emissive effect

Photovoltaic effect

Photoconductive effect

None of these

Answer : c

Q5. LED gives off visible light from

1. A region of depletion layer
2. P region alone
3. N region alone
4. Both p and n regions

Answer : a

Q6. LEDs have response time of the order of

1. 1 ns
2. 1 ns
3. 100 ns
4. 1µs

Answer : b

Q7. In LED , when excited electrons revert from conduction band to valence band, the phenomenon utilized is

1. Radioactive recombination
2. Formation of photons
3. Energy transfer from one electron to other
4. None of these

Answer : a

Q8. LEDs fabricated from Ga As P emit radiation in the

1. Ultraviolet region
2. Infrared region
3. Visible region
4. None of these

Answer : c

Q9. A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is

1. 100
2. 99
3. 01
4. 99

Answer : a

Q10. At 25oC , the collector-emitter voltage drop of a silicon transistor at saturation is approximately

1. 1 V
2. 3 V
3. 5 V
4. 7 V

Answer : a

Q11. The reverse bias breakdown of high speed silicon transistors is due to Zener breakdown mechanism at

1. Both the junctions
2. Base-collector junction and avalanche breakdown mechanism at base-emitter junction
3. Base-emitter junction and avalanche breakdown mechanism at base-collector junction
4. None of these

Answer : c

Q12. Almost all resistors are made in a monolithic integrated circuit

1. During the emitter diffusion
2. While growing the epitaxial layer
3. During the base diffusion
4. During the collector diffusion

Answer : a

Q13. An SCR triggered by a current pulse through its gale can be turned off by

1. Giving another pulse of the same polarity to the gate
2. Giving pulse to the cathode
3. Giving pulse to the anode
4. Reversing the polarity of anode and cathode voltage

Answer : d

Q14. The Ebers-Mall model is applicable to

1. Bipolar junction transistors
2. NMOS transistors
3. Unipolar junction transistors
4. Junction field-effect transistors

Answer : a

Q15.  In an intrinsic semiconductor the free electron concentration depends on

1. Effective mass of electrons only
2. Effective mass of holes only
3. Temperature of the semiconductor
4. Width of the forbidden energy band of the semiconductor

Answer : c