Question

The metal oxide rectifier used for the electrolytic process is placed along with the transformer:
(A) Inside the oil
(B) Outside the transformer but near to it
(C) Outside the transformer but far from it
(D) Half immersed in the oil

Answer 1

Hint: Metal oxide rectifiers are generally the copper-oxide rectifiers. They convert an AC signal coming from an AC source to the DC signal. For the electrolytic process, DC current is required therefore a rectifier is used along with the transformer in order to convert the AC current into DC.

Complete step by step solution:
Metal oxide rectifiers are made of Copper oxide, which acts as a semiconductor. A number of plates of this rectifier are placed next to each other and are connected in series. They are designed to protect the circuit from any damage caused by an abrupt change in the amount of current.
Since the rectifier is made of metal oxide, it behaves as a base and it may react with the electrolytes, for this reason, it is kept inside oil to prevent corrosion of the rectifier.

Therefore option (A) is the correct answer.

Additional Information:
Rectifiers are the semiconductor devices that convert AC current into DC using their properties of varying resistance. A simple P-N junction can act as a rectifier. An AC source produces a current that constantly switches its direction; when this source is connected to a P-N junction, for half of the signal, the current will pass through the P-N diode as it will be in the forward bias. But as the direction of the current changes, it will make the P-N diode reverse biased. This will not allow the current to pass. Thus only DC can pass through a rectifier.

Note: There are many types of rectifiers present in the electronic industry and metal oxide rectifiers generally have lower efficiency than the other ones present. But the applications like electroplating, which involve electrolysis still use metal oxide rectifiers due to its property of lower forward voltage drop.