In a backward wave oscillator the wave travelling along the line winds itself ba

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Question
In a backward wave oscillator the wave
Options
A. travelling along the line winds itself back and forth
B. progresses only in forward direction
C. progresses only in backward direction
D. either (a) or (c)

Correct Answer

travelling along the line winds itself back and forth

Explanation

It 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.

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5. 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

9. 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

10. The real part of complex dielectric constant and tan? for a dielectric are 2.1 and 5 x 10^-4 at 100 Hz respectively. The imaginary part of dielectric constant at 100 Hz is
Options
A. 1.05 x 10^-3
B. 2.1 x 10^-3
C. 5 x 10^-3
D. 1.05 x 10^-2

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