MyCompetitiveExams Logo MyCompetitiveExams
MyCompetitiveExams Logo MyCompetitiveExams
Search 1,140+ Questions
Chapters, formulas, speed tricks
→
⚡ Brahmastra NEET 2027
720 MARKS

Dynamic 180-question full-length simulator mixed dynamically from all 6 years for 2027 & 2026 aspirants.

Launch Brahmastra 2027 Test →
Start Practice →
100% Free · No Login Required
Q.6 Physics · Section A ⭐ 360° Option Elimination Active
Vault ↗

NEET 2024 Physics Question 6 Solution

Topic: Semiconductor Electronics · Official NTA Booklet Code T1
NEET 2024 Physics Question 6: Logic Gate Equivalent Circuit Analysis

Question

The output (Y) of the given logic gate is similar to the output of an/a:

✓
Verified Against NTA Final Answer Key
Option (2) : AND gate
📚 Semiconductor Electronics Easy
📋 Given Parameters & Problem Setup
Input A Gate NAND gate with shorted inputs (acts as NOT gate)
Input B Gate NOR gate with shorted inputs (acts as NOT gate)
Output Gate NOR gate combining the inverted inputs
⚡

The 30-Second Exam Hall Shortcut: ⚡ De Morgan’s Inversion Shortcut

⏱️ Save ~40 seconds

Shorted NAND = NOT(A); Shorted NOR = NOT(B); Output NOR on (Ā, B̄) gives NOT(Ā + B̄) = A · B (AND Gate)!

1 A single-input NAND gate produces Ā (NOT A).
2 A single-input NOR gate produces B̄ (NOT B).
3 These feed into a NOR gate: Output Y = NOT(Ā + B̄).
4 By De Morgan’s First Theorem: NOT(Ā + B̄) = NOT(NOT A) · NOT(NOT B) = A · B.
5 The expression Y = A · B is the truth function of a standard AND gate -> Option (2) in 10 seconds!
🛡️
Why You Can 100% Trust This Shortcut: Boolean Algebra & De Morgan’s Theorems (NOT(A + B) = Ā · B̄).
📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Function of Input Gate for Terminal A

The top gate is a two-input NAND gate whose inputs are shorted together to receive a common signal A. The Boolean operation of a NAND gate on identical inputs simplifies directly to an inverter (NOT gate):

YA=A⋅A‾=A‾Y_A = \overline{A \cdot A} = \overline{A}
Step 2

Function of Input Gate for Terminal B

The bottom gate is a two-input NOR gate whose inputs are shorted together to receive a common signal B. The Boolean operation on identical inputs also simplifies to an inverter (NOT gate):

YB=B+B‾=B‾Y_B = \overline{B + B} = \overline{B}
Step 3

Final Stage NOR Gate Combination

The signals Y_A = Ā and Y_B = B̄ serve as inputs to the final NOR gate. The output Y is the NOR operation on Ā and B̄:

Y=YA+YB‾=A‾+B‾‾Y = \overline{Y_A + Y_B} = \overline{\overline{A} + \overline{B}}
Step 4

Simplification Using De Morgan’s Theorem

Applying De Morgan’s law to the complement of a sum yields the product of the complements:

Y=A‾‾⋅B‾‾=A⋅BY = \overline{\overline{A}} \cdot \overline{\overline{B}} = A \cdot B
⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan
1 (1)
✗ Incorrect
Verdict & Scientific Reason:

Represents A + B, whereas the circuit performs A · B.

⚠️
Student Fallacy (Why candidates pick this trap): Confusing De Morgan’s law and assuming the final NOR gate acts as an OR gate.
2 (2)
✓ 100% Correct
Verdict & Scientific Reason:

Boolean algebraic simplification proves Y = A · B identically.

💡
Why this is airtight: None.
3 (3)
✗ Incorrect
Verdict & Scientific Reason:

NAND would require an extra inversion at the output (NOT(A · B)).

⚠️
Student Fallacy (Why candidates pick this trap): Ignoring the inversion bubble of the final NOR gate.
4 (4)
✗ Incorrect
Verdict & Scientific Reason:

Only the final physical component is a NOR gate, but its inputs are already inverted.

⚠️
Student Fallacy (Why candidates pick this trap): Looking only at the final symbol without considering input inversions.
⚠️

NTA Trap Alert: Looking Only at the Final Gate

Hasty students look at the final gate symbol, see a NOR shape, and immediately circle NOR gate without checking the inverted inputs.

🛡️ How to avoid the -1 mark: Always write down the intermediate signals on your scratchpad: Y = NOT(Ā + B̄) = A · B.
📖

Core NEET Syllabus Standard

Physics Core Digital Electronics · Semiconductor Electronics: Materials, Devices and Simple Circuits Standard Benchmark
Core Scientific Principle Tested:

"Inverting both inputs to a NOR gate converts its functionality to that of an AND gate (bubbled NOR = AND)."

Syllabus Focus: Logic Gates and Universal Gate Combinations
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗
Inverted inputs flip the gate: NOR becomes AND, clear and straight!

Ready to attempt under real exam pressure?

Test your speed and accuracy in the authentic 200-minute timed NTA simulator.

Launch NEET 2024 CBT Test →

Spotted a mistake in this solution? Report an error ([email protected])

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2024 question papers and NEET answer keys for private study, research, and non-commercial educational practice under Fair Dealing (Section 52(1)(a) of the Indian Copyright Act, 1957). Not affiliated with or endorsed by NTA or NMC.

Solve 4 NEET Questions a Day — One per Subject

Cover all 1,140 official NEET questions in 285 days at your own pace. Progress is saved on your device. No login needed.