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.Management Sciences
Category: Rectifiers and Converters
In a grid control of mercury arc rectifiers when the grid is made positive relative to cathode, then it the electrons on their may to anode.
A. accelerates
B. decelerates
C. any of the above
D. none of the above
In a mercury arc rectifier characteristic blue luminosity is due to_____________?
A. colour of mercury
B. ionization
C. high temperature
D. electron streams
Which of the following statement is incorrect ?
A. Copper oxide rectifier is a linear device
B. Copper oxide rectifier is not a perfect rectifier
C. Copper oxide rectifier has a low efficiency
D. Copper oxide rectifier finds use in control circuits
E. Copper oxide rectifier is not stable during early life
In a phase-shift control method, the phase shift between anode and grid voltages can be achieved by means of______________?
A. shunt motor
B. synchronous motor
C. induction regulator
D. synchronous generator
A mercury arc rectifier possesses __________ regulation characteristics
A. straight line
B. curved line
C. exponential
D. none of the above
In a single phase rotary converter the number of slip rings will be_____________?
A. two
B. three
C. four
D. six
E. none
In a rotary converter armature currents are______________?
A. d.c. only
B. a.c. only
C. partly a.c. and partly d.c.
In a mercury pool rectifier, the voltage drop across its electrodes___________?
A. is directly proportional to load
B. is inversely proportional to load
C. varies exponentially with the load current
D. is almost independent of load current
Mercury, in arc rectifiers, is chosen for cathode because________________?
A. its ionization potential is relatively low
B. its atomic weight is quite high
C. its boiling point and specific heat are low
D. it remains in liquid state at ordi¬nary temperature
E. all of the above
The internal efficiency of a mercury arc rectifier depends on___________?
A. voltage only
B. current only
C. voltage and current
D. r.m.s. value of current
E. none of the above
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