NEET UG 2021 · Physics · Question 46
NEET 2021 Physics, question 46
Question 46 of the NEET 2021 paper (code O1) is a Physics question from Semiconductor Electronics: Materials, Devices and Simple Circuits. Its idea, Logic Gate Waveform Analysis, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 3.
Updated 2026-10-08
Q46 · Physics
For the given circuit, the input digital signals are applied at the terminals A, B and C. What would be the output at the terminal ?
The figure, described in words
Timing diagram t1–t6: A pulses high (5 V) during t1–t2, t3–t4, t5–t6; B high during t2–t4; C high before t2 and after t4, low t2–t4. Circuit: AND(A,B) and NAND(B,C) feed an OR gate giving y.
- 1[waveform: y = 0 V throughout t1–t6]
- 2[waveform: 0 V before t1, 5 V from t1 to t3, 0 V from t3 to t6, 5 V after t6]
- 3[waveform: y = 5 V constant throughout]Official answer
- 4[waveform: 5 V before t1, 0 V from t1 to t3, 5 V from t3 to t6, 0 V after t6]
Official answer: option 3 · NTA final answer key
Same idea
The only question on Logic Gate Waveform Analysis
No other NEET paper from 2017–2026 tested this exact idea.
Logic Gate Waveform Analysis: every question and how it was framed
The chapter
Semiconductor Electronics: Materials, Devices and Simple Circuits in ten years of NEET
27 questions from 2017–2026, asked in 10 of 10 papers, about 2.6 a paper. Logic Gates alone had 10.