The following figure shows device X with input and output signals. The device is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Half wave Rectifier
The input is an alternating (sinusoidal) voltage. In the output only the positive half cycles remain, and in place of each negative half cycle there is a gap of one half period. A device that passes one half of each cycle and blocks the other half is a half wave rectifier.
Option (1) Half wave Rectifier — Correct. Only the positive halves pass; the negative halves are removed.
Option (2) Full wave Rectifier — Incorrect. A full wave rectifier would turn the negative halves into positive humps, so the humps would follow one another with no gaps.
Option (3) Transistor — Incorrect. A transistor amplifier would give a full sine wave (amplified, possibly inverted), not separated humps.
Option (4) Transformer — Incorrect. A transformer changes the amplitude of an AC voltage, but its output is still a complete sine wave.
NCERT (2026-27):
Application of Junction Diode as a Rectifier – “… Therefore, in the positive half-cycle of ac there is a current through the load resistor RL and we get an output voltage, as shown in Fig. 14.18(b), whereas there is no current in the negative half-cycle. … Since the rectified output of this circuit is only for half of the input ac wave it is called as half-wave rectifier.”