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

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

Choose the right option among the alternatives – A thyristor goes into full conduction in its forward direction when anode/cathode/gate is positive with respect to its anode/cathode/gate and a turn-on voltage or current signal in the form of a pulse is given to its anode/ cathode/gate.

A

Cathode, anode, gate

B

Gate, anode, cathode

C

Anode, cathode, gate

D

Anode, gate, cathode

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

Seven people A, B, C, D, E, F and G live on separate floors of a 7-floor building. Ground floor is numbered 1, first floor is numbered. 2 and so on until the topmost floor is numbered 7. Each one of these having a different cars-Cadillac, Ambassador, Fiat, Maruti, Mercedes, Bedford and Fargo but not necessarily in the same order. Only three people live above the floor on which A lives. Only one person lives between A and the one having a car Cadillac. F lives immediately below the one having a car Bedford. The one having a car Bedford lives on an even-numbered floor. Only three people live between the ones having a car Cadillac and Maruti. E lives immediately above C. E is not having a car Maruti. Only two people live between B and the one having a car Fargo. The one having a car Fargo lives below the floor on which B lives. The one having a car Fiat does not live immediately above D or immediately below B. D does not live immediately above or immediately below A. G does not have a car Ambassador. Question : How many people live between the floors on which D and the one having a car Bedford ?

A

One

B

Two

C

Three

D

Four

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

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

Potential of earth is – 50 V. If the potential difference between anode and cathode (earthed) is measured as 150 V, actual voltage on anode is __________

A

0 V

B

100 V

Assertion (A) For a galvanic cell, oxidation takes place at anode and reduction at cathode.
Reason (R) Electrons in the external circuit move from anode to cathode

A

Both A and R are true and R is the correct explanation of A

B

Both A and R are true, but R is not the correct explanation of A

C

A is true, but R is false

D

A is false, but R is true

With reference to street-lighting, how do Mercury vapour lamps differ from LED lamps? 1. Mercury vapour lamps use a fraction of the energy used in the case of LED lamps. 2. LEDs have a lower radiance than mercury arc lamps. 3. Mercury lamps are eco-friendly as they require low voltages than LED lamps to operate. Select the correct answer using the code given below.

A

2 only

B

3 only

C

1 and 3 only

D

1, 2 and 3

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

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

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