A. 5 to 10 per cent
B. 15 to 20 per cent
C. 25 to 30 per cent
D. none of the above
Related Mcqs:
- Selenium rectifier can be operated at temperatures as high as____________?
A. 25°C
B. 40°C
C. 60°C
D. 75°C - When a rectifier is loaded which of the following voltage drops take place ?
A. Voltage drop in transformer reactance
B. Voltage drop in resistance of transformer and smoothing chokes
C. Arc voltage drop
D. All of the above - The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________?
A. anode drop and cathode drop
B. anode drop and arc drop
C. cathode drop and arc drop
D. anode drop, cathode drop and arc drop - The voltage drop at anode, in a mercury arc rectifier is due to_____________?
A. self restoring property of mercury
B. high ionization potential
C. energy spent in overcoming the electrostatic field
D. high temperature inside the rectifier - 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 - The cathdde voltage drop, in a mercury arc rectifier, is due to_____________?
A. expenditure of energy in ionization
B. surface resistance
C. expenditure of energy in overcoming the electrostatic field
D. expenditure of energy in liberating electrons from the mercury - In selenium rectifiers efficiencies ranging from _______ to _______ percent are attainable?
A. 25, 35
B. 40, 50
C. 60, 70
D. 75, 85 - The applications of selenium rectifiers are usually limited to potential of_____________?
A. 10 V
B. 30 V
C. 60 V
D. 100 V
E. 200 V - A commutating rectifier consists of commutator driven by___________?
A. an induction motor
B. a synchronous motor
C. a D.C. series motor
D. a D.C. shunt motor - In a mercury arc rectifier positive ions are attracted towards______________?
A. anode
B. cathode
C. shell bottom
D. mercury pool
