Which is the wrong statement in following sentences?

A device in which P and N-type semiconductors are used is more useful then a vacuum type because 

(a) Power is not necessary to heat the filament

(b) It is more stable

(c) Very less heat is produced in it

(d) Its efficiency is high due to a high voltage across the junction

Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level: