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

Related Mcqs:

1. Which of the following rectifiers have been used extensively in supplying direct current for electroplating ?

   A. Copper oxide rectifiers
   B. Selenium rectifiers
   C. Mercury arc rectifiers
   D. Mechanical rectifiers
   E. None of the above

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

   A. Telephones
   B. Relays
   C. Time switches
   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. In a glass bulb mercury arc rectifier the maximum current rating is restricted to___________?

   A. 2000 A
   B. 1500 A
   C. 1000 A
   D. 500 A

5. 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

6. Which of the following is the loss within the mercury arc rectifier chamber ?

   A. Voltage drop in arc
   B. Voltage drop at the anode
   C. Voltage drop at the cathode
   D. All of the above

7. 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

8. 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

9. 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

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

    A. Rectifiers
    B. Motor converters
    C. Motor-generator sets
    D. Rotary converters
    E. All of the above