Consider the following statements about rectifiers:
(A) A full-wave rectifier gives a rectified output during both the positive and the negative half of the ac input.
(B) A full-wave rectifier is a more efficient circuit for getting rectified voltage than a half-wave rectifier.
(C) The full-wave rectifier circuit that does not use a centre-tap transformer needs only two diodes.
(D) The output of a full-wave rectifier without a filter is in the form of pulses shaped like complete sine waves.
Which of the above statements are incorrect?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (C) and (D) only
A full-wave rectifier uses both halves of the ac cycle, while a half-wave rectifier uses only one. The usual full-wave circuit has two diodes and a centre-tap transformer.
(A) A full-wave rectifier gives a rectified output during both the positive and the negative half of the ac input. — Correct statement. One diode conducts in the positive half and the other in the negative half. So the load gets current, in the same direction, in both halves.
(B) A full-wave rectifier is a more efficient circuit for getting rectified voltage than a half-wave rectifier. — Correct statement. It uses the whole input cycle. A half-wave rectifier uses only one half of each cycle.
(C) The full-wave rectifier circuit that does not use a centre-tap transformer needs only two diodes. — Incorrect statement. The full-wave circuit without a centre tap needs four diodes. Two diodes are enough only with a centre-tap transformer.
(D) The output of a full-wave rectifier without a filter is in the form of pulses shaped like complete sine waves. — Incorrect statement. Each pulse is only half of a sine wave, and all pulses are in one direction.
NCERT (2026-27):
Application of Junction Diode as a Rectifier – “… gives output rectified voltage corresponding to both the positive as well as negative half of the ac cycle. Hence, it is known as full-wave rectifier. …”
Application of Junction Diode as a Rectifier – “… Obviously, this is a more efficient circuit for getting rectified voltage or current than the half-wave rectifier.”
Application of Junction Diode as a Rectifier – “… (Note that there is another circuit of full wave rectifier which does not need a centre-tap transformer but needs four diodes.) …”
Application of Junction Diode as a Rectifier – “The rectified voltage is in the form of pulses of the shape of half sinusoids. …”