Discussion
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- Question
Assertion (A): PIN diode is used as a fast switch.
Reason (R): PIN diode has very high resistance when reverse biased and very low resistance when forward biased.
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R are correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct
- Correct Answer
- Both A and R are correct and R is correct explanation of A
ExplanationA PIN diode has an intrinsic (i) layer between p and n layers. When reverse bias is applied depletion layers are formed at p-i and i-n junctions.The effective/width of depletion layer increases by the width of i layer. It can be used as a voltage controlled attenuator.
At high frequencies the rectification effect ceases and impedance of diode is effectively that of i layer.
This impedance varies with the applied bias. It is used in high frequency switching circuits, limiters, modulators etc.
More questions
- 1. The maximum signal propagation time of a geosynchronous satellite transmission is about __________ millisecond.
Options- A. 540
- B. 270
- C. 135
- D. 1080 Discuss
Correct Answer: 270
- 2. In carbon resistor colour code, the third band is red. It indicates
Options- A. two zeros
- B. three zeros
- C. multiplier is 0.01
- D. multiplier is 0.1 Discuss
Correct Answer: two zeros
- 3. Low-orbit satellites are not used for communications because they
Options- A. produce sonic booms
- B. do not provide 24 hour/ day contact to the users on Earth
- C. heat up and melt
- D. none Discuss
Correct Answer: heat up and melt
- 4. When a thyristor is conducting, the voltage drop across it is about
Options- A. 1 V
- B. 10 V
- C. 100 V
- D. 0.1 V Discuss
Correct Answer: 1 V
- 5. In a TWT the phase velocity of the axial component of the field on the slow wave structure is kept
Options- A. equal to velocity of electron
- B. slightly less than velocity of electron
- C. slightly more than velocity of electron
- D. equal to velocity of light in free space Discuss
Correct Answer: equal to velocity of electron
- 6. Assertion (A): SUS is a PUT and avalanche diode connected between gate and cathode
Reason (R): SBS has two SUS inbuilt together and connected in anti-parallel
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct Discuss
Correct Answer: Both A and R correct but R is not correct explanation of A
- 7. In a CRO which of the following is not a part of electron gun
Options- A. cathode
- B. grid
- C. accelerating anode
- D. X - Y plates Discuss
Correct Answer: X - Y plates
Explanation:
Electron gun consists of cathode, grid and accelerating anode.- 8. Which of the following can be accessed only sequentially?
Options- A. Floppy disk
- B. Hard disk
- C. Magnetic tape
- D. ROM Discuss
Correct Answer: Magnetic tape
Explanation:
Magnetic tape can be accessed only sequentially.- 9. Which of the following is not a valid variable name in C?
Options- A. p o, t
- B. p o t
- C. po_t
- D. p_ot Discuss
Correct Answer: p o, t
Explanation:
Comma is not allowed.- 10. A magnet does not attract
Options- A. nickel
- B. iron
- C. copper
- D. iron and copper Discuss
Correct Answer: copper
Explanation:
Only copper is non-magnetic.
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