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Practice Test: Question Set - 02


1. In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as
    (A) Maximum grid voltage
    (B) Critical grid voltage
    (C) Any of the above
    (D) None of the above

2. 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

3. Which of the following mercury arc rectifier will deliver least undulating current?
    (A) Six-phase
    (B) Three-phase
    (C) Two-phase
    (D) Single-phase

4. The cathode 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

5. 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

6. In a mercury arc rectifier positive ions are attracted towards
    (A) Anode
    (B) Cathode
    (C) Shell bottom
    (D) Mercury pool

7. A rotary converter operates at a
    (A) Low power factor
    (B) High power factor
    (C) Zero power factor
    (D) None of the above

8. Which of the following are the applications of D.C. system?
    (A) Battery charging work
    (B) Arc welding
    (C) Electrolytic and electrochemical processes
    (D) All of the above

9. A rotary converter is a single machine with
    (A) One armature and one field
    (B) Two armatures and one field
    (C) One armature and two fields
    (D) None of the above

10. The ionization potential of mercury is approximately
    (A) 5.4 V
    (B) 8.4 V
    (C) 10.4 V
    (D) 16.4 V

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