Discussion
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- Question
The frequency of oscillation in a backward wave oscillator can be changed by
Options- A. varying the voltage which controls beam velocity
- B. varying the beam current
- C. both by varying the beam current and by light varying the voltage which controls beam velocity
- D. changing the rate of thermionic emission
- Correct Answer
- varying the voltage which controls beam velocity
ExplanationIt is somewhat similar to TWT and can deliver microwave power over a wide frequency band.It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.
The growing RF wave travels in opposite direction to the electron beam.
The frequency of wave can be changed by changing the voltage which controls the beam velocity.
Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.
It features are:
1. Frequency range - 1 GHz to 1000 GHz.
2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).
It is used as signal source in transmitters and instruments.
More questions
- 1. The characteristic impedance of a cable is about
Options- A. 300 ?
- B. 50 ?
- C. 5 ?
- D. 2 ? Discuss
Correct Answer: 50 ?
- 2. A copper atom is neutral. Its core has a net charge of
Options- A. 0
- B. + 1
- C. - 1
- D. + 2 Discuss
Correct Answer: + 1
- 3. The characteristics of which device has peak point and valley point
Options- A. SCR
- B. PUT
- C. SCS
- D. Shockley diode Discuss
Correct Answer: PUT
- 4. Schrodinger wave equation is partial differential equation.
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. The output frequency of a cycloconverter can be changed by changing the firing angle.
Options- A. True
- B. False Discuss
Correct Answer: False
- 6. Most of the memory chips in static RAM
Options- A. do not require any supply
- B. need 2 V supply
- C. need 5 V supply
- D. need 12 V supply Discuss
Correct Answer: need 5 V supply
Explanation:
Digital chips need 5 V supply.- 7. In crystalline solids, atoms are stacked in a regular manner.
Options- A. True
- B. False Discuss
Correct Answer: True
- 8. The classes of solid dielectrics are
Options- A. A, B, C, D, E, F, H
- B. A E B F H C D
- C. Y A E B F H C
- D. A E B F H C Discuss
Correct Answer: Y A E B F H C
- 9. The unit for mmf is
Options- A. A
- B. Wb
- C. T
- D. V Discuss
Correct Answer: A
- 10. In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally
Options- A. equal
- B. different
- C. equal or different
- D. different but sometimes equal Discuss
Correct Answer: equal
Explanation:
Firing angles are kept equal to get symmetrical output voltage.
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