Related Questions

In selenium rectifiers efficiencies ranging from ______ to ______ percent are attainable
A 25, 35
B 40, 50
C 60, 70
D 75, 85
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
The metal rectifiers, as compared to mercury arc rectifiers
A operate on low temperatures
B can operate on high voltages
C can operate on heavy loads
D give poor regulation
E none of the above
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
Glass rectifiers are usually made into units capable of D.C. output (maximum continuous rating) of
A 100 A at 100 V
B 200 A at 200 V
C 300 A at 300 V
D 400 A at 400 V
E 500 A at 500 V
A recent study shows that selenium , a mineral →bfound in in seafood, →cis linked to →dreducethe human cancer risk
A a
B b
C c
D d
Selenium is _____ semiconductor.
A Extrnisic
B Intmisic
C N-type
D P-type
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
Selenium rectifier can be operated at temperatures as high as
A 25°C
B 40°C
C 60°C
D 75°C
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 All of the above

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