Which of the following methods may be used to convert A.C. system to D.C ?

Related Mcqs:

1. Ageing of a selenium rectifier may change the output voltage by__________?

   A. 5 to 10 per cent
   B. 15 to 20 per cent
   C. 25 to 30 per cent
   D. none of the above

2. 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

3. Which of the following rectifiers are primarily used for charging of low voltage batteries from AC supply ?

   A. Mechanical rectifiers
   B. Copper oxide rectifiers
   C. Selenium rectifiers
   D. Electrolytic rectifiers
   E. Mercury arc rectifiers

4. The metal rectifiers are preferred to valve rectifiers due to which of the following advantages ?

   A. They are mechanically strong
   B. They do not require any voltage for filament heating
   C. Both (A) and (B)
   D. None of the above

5. 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

6. In which of the following appUcations, direct current is absolutely essential ?

   A. Illumination
   B. Electrolysis
   C. Variable speed operation
   D. Traction

7. Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required ?

   A. Motor-generator set
   B. Motor converter
   C. Rotary converter
   D. Mercury arc rectifier

8. Which of the following metals is generally manufactured by electrolysis process ?

   A. Load
   B. Aluminium
   C. Copper
   D. Zinc
   E. None of the above

9. In which of the following equipment direct current is needed ?

   A. Telephones
   B. Relays
   C. Time switches
   D. All of the above

10. Which of the following are the applications of D.C. system ?

    A. Battery charging work
    B. Arc welding
    C. Electrolytic and electro-chemical processes
    D. Arc lamps for search lights
    E. All of the above