Electronics Engineering Objective Questions { Microwave Devices and Circuits }

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92. The term LASER is an abbreviation for

A. Low amplification signal emitting radiowaves

B. Last aligned sound emitting radiowaves

C. Light amplification by simulated emission of radiation

D. None of the above

93. MASER finds application in

A. Opto electronics

B. Fibre optics

D. All of the above

94. The skin effect causes current to flow

A. in the centre of the conductor

B. near the surface of the conductor

C. through central core of the conductor

D. uniformly through the conductor

95. In a waveguide the energy is propagated bY

A. voltage different

B. current variations

C. varying magnetic fields

D. varying magnetic and electric fields

96. A duplexer is used

A. to couple two different antennas to transmitter without mutual interference

B. to allow the one antenna to be used for reception or transmission without mutual interference

C. to prevent interference between two antennas when they are connected to a receiver

D. to increase the speed of the pulses in pulses radar

97. Indicate the false statement : Transit time in microwave bubes will be reduced if

A. the electrodes are brought closer together

B. a higher anode current is used

C. multiple or coaxial leads are used

D. the anode voltage is made larger

98. Cassegrain feed is used with a parabolic reflector to

A. increase the gain of the system

B. increase the beam width of the system

C. reduce the size of the main reflector

D. allow the feed to be placed at a convenient point

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