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.

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

তড়িৎ রাসায়নিক কোষের emf = ?i. E° Anode(ox) + E°Cathode (Red) 11. E Cathode(Red) - E°Anode (Red) 111. E° Anode(ox) - E°Cathode (Red) নিচের কোনটি সঠিক?

A

i ও ii

B

i ও iii

C

ii ও iii

D

i, ii ও iii

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 a three-phase mercury arc rectifiers each anode conducts for

A

One-third of a cycle

B

One-fourth of a cycle

C

One-half a cycle

D

Two-third of a cycle

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

Caustic soda is produced in a mercury cell having anode and cathode made respectively of moving mercury and

A

Moving mercury and graphite

B

Graphite and moving mercury

C

Moving mercury and carbon

D

Moving mercury and crimped steel wire

If cathode and anode connections in a mercury arc rectifier are inter changed

A

The rectifier will not operate

B

Internal losses will be reduced

C

Both ion and electron streams will move in the same direction

D

The rectifier will operate at reduced efficiency

In a mercury arc rectifier______ flow from anode to cathode

A

ions

B

electrons

C

ions and electrons

D

any 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 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

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.

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