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- Question
Resistivity of copper is lower than that of nickel. When a small percentage of copper is added to nickel, the resistivity
Options- A. increases
- B. decreases
- C. may increase or decrease
- D. remains the same
- Correct Answer
- increases
- 1. Which of these commutation methods is used in AC-DC converters?
Options- A. Class A
- B. Class C
- C. Class D
- D. Class F Discuss
- 2. Match the following:
List I List II A. Servomotor 1. Error detector B. Amplidyne 2. Transducer C. Potentiometer 3. Actuator D. Flapper valve 4. Power amplifier
Options- A. A-3, B-1, C-2, D-4
- B. A-4, B-3, C-2, D-1
- C. A-3, B-4, C-1, D-2
- D. A-3, B-4, C-2, D-1 Discuss
- 3. Match the following:
List I List II A. Simple dipole 1. 
B. Omnidirectional antenna 2. 
C. Loop antenna 3. 
Options- A. A-1, B-2, C-3
- B. A-2, B-1, C-1
- C. A-3, B-2, C-1
- D. A-1, B-1, C-2 Discuss
- 4. Match the following:
List I List II A. C 1. 7 eV B. Si 2. 1.15 eV C. Ge 3. 0.75 eV D. Sn 4. 0.1 eV E. Pb 5. 0 eV
Options- A. A-2, B-3, C-4, D-5, E-1
- B. A-1, B-2, C-3, D-4, E-5
- C. A-3, B-1, C-2, D-5, E-4
- D. A-4, B-5, C-1, D-2, E-3 Discuss
- 5. The effect of earth's magnetic field on radiowaves is minimum when
Options- A. the electric field lines of radio waves and flux line of earth's magnetic field are in the same direction
- B. the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles
- C. the electric field lines of radiowaves and flux lines of earth's magnetic field oppose each other
- D. both (b) and (c) Discuss
- 6. The earliest uses of electromagnetic waves were
Options- A. point to point communication
- B. radar
- C. both (a) and (b)
- D. neither (a) nor (b) Discuss
- 7. As per Matthiessen's rule, the total resistivity r of a conductor can be written as r = ri + aT, where ri and a are constants and T is absolute temperature. At very low temperatures
Options- A. aT = 0
- B. aT > ri
- C. aT ? ri
- D. aT < ri Discuss
- 8. In p mode of operation of magnetron the spikes due to phase focussing effect rotate at an angular velocity corresponding to
Options- A. one pole/cycle
- B. two pole/cycle
- C. four pole/cycle
- D. six pole/cycle Discuss
- 9. In a multicavity klystron amplifier the electron velocity of the order of
Options- A. 10 m/s
- B. 103 m/s
- C. 106 m/s
- D. 1012 m/s Discuss
- 10. Which modes of circular wave guides have circular symmetry?
Options- A. TE11
- B. TE11 and TE21
- C. TE01
- D. TE01 and TM01 Discuss
More questions
Correct Answer: Class F
Explanation:
Class F is natural commutation AC = DC converter use natural (or line) commutation.
Correct Answer: A-3, B-4, C-2, D-1
Correct Answer: A-2, B-1, C-1
Correct Answer: A-1, B-2, C-3, D-4, E-5
Correct Answer: the electric field lines of radio waves and flux line of earth's magnetic field are in the same direction
Correct Answer: both (a) and (b)
Correct Answer: aT < ri
Explanation:
At very low temperatures a T ? 0. Since resistivity has a finite value even at low temperature, a T < ri.
Correct Answer: two pole/cycle
Correct Answer: 106 m/s
Correct Answer: TE01 and TM01
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