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Semiconductors appeared 32 times across 3 years — 3.7% of Physics. This question is from Logic Gates and Truth Tables.

Year 2026 2025 2024 Total
Questions 9 15 8 32

The truth table for this given circuit is:
Logic gate circuit diagram for Q32 - JEE Main 2024 29 January Shift 2
The diagram displays a logic circuit comprising two AND gates, one NOT gate, and an OR gate to produce output Y.

Solution & Explanation

Related Formula

The Boolean algebraic relationships for standard gates are:

  • AND Gate: Y = A · B
  • NOT Gate: Y = A
  • OR Gate: Y = A + B
Core Logic

Analyzing the connections of the logic circuit shown in the diagram:

  • Input A is passed directly to the top AND gate.
  • Input A is also passed through a NOT gate, giving A, which is supplied to the bottom AND gate.
  • Input B is connected directly to both the top and bottom AND gates.
  • Hence:

  • Output of the top AND gate is: A · B
  • Output of the bottom AND gate is: A · B
  • Both outputs are then combined by an OR gate to give the final output Y:

Y = (A · B) + ( A · B)
Step 1: Simplify the Boolean Expression

Using Boolean algebra, factor out B:

Y = (A + A) · B

Since A + A = 1:

Y = 1 · B

Y = B

Simplified Boolean algebra logic circuit for Q32 - JEE Main 2024 29 January Shift 2
The diagram displays a logic circuit comprising two AND gates, one NOT gate, and an OR gate to produce output Y.

Step 2: Construct the Truth Table

Because the output Y is functionally identical to B, the truth table columns for B and Y must be exactly the same:

  • When B = 0, Y = 0
  • When B = 1, Y = 1
  • This yields the matching truth table in Option 2.

Pattern Recognition

Observe: Y = A · B + A · B. Whenever B is a common factor to both paths of the AND-OR configuration, it suggests the expression can be simplified directly to B because the state of A becomes irrelevant (A + A = 1).

Chapter Mix

Class 12 Physics: Semiconductors

Reference Study Guides

More Semiconductors Previous-Year Questions — Page 7

Q49 jee_main_2024_31_jan_evening Logic Gates
The output of the given circuit diagram is
Logic Gates diagram for Q49 - JEE Main 2024 Evening
The image shows a logic circuit composed of NOT gates, OR gates, and a final NOR gate.
  • A.
    ABY
    000
    100
    010
    111
  • B.
    ABY
    000
    101
    011
    110
  • C.
    ABY
    000
    100
    010
    110
  • D.
    ABY
    000
    100
    011
    110

Solution

Related Formula

Boolean Algebra expressions for logic gates: NOT: A OR: A + B NOR: A + B

Core Logic

Analyze the paths from inputs A and B to the final output Y.

Logic Gates diagram for Q49 - JEE Main 2024 Evening
The image shows a logic circuit composed of NOT gates, OR gates, and a final NOR gate.

Step 1: Intermediate Signals

Top OR gate inputs: A directly, and B inverted (B). Top OR gate output: A + B

Bottom OR gate inputs: A inverted (A), and B directly. Bottom OR gate output: A + B

Step 2: Final Gate Evaluation

The final gate is a NOR gate taking the two intermediate outputs as its inputs.

Y = (A + B) + ( A + B)

Notice that the inner sum simplifies cleanly:

(A + A) + (B + B)

Since A + A = 1 and B + B = 1, the inner term is 1 + 1 = 1.

Y = 1 = 0
Step 3: Conclusion

The output Y is always 0 regardless of the inputs A and B. Checking the truth tables, only option 3 satisfies Y=0 for all conditions.

Pattern Recognition

When a Boolean expression groups a variable and its exact complement together in an OR configuration (A and A), the result instantly hits logic 1. Feeding 1 into any NOR gate guarantees a 0 output universally.

Chapter Mix

Class 12 Physics: Semiconductor Electronics

Q jee_main_2024_31_jan_morning Logic Gates
Identify the logic operation performed by the given circuit.
Logic Gates diagram for Q32 - JEE Main 2024 Morning
Two inputs passing through NOT gates before entering a NAND gate.
  • A. NAND
  • B. NOR
  • C. OR
  • D. AND

Solution

Related Formula
Y = A · B (NAND) Y = A + B (De Morgan's)
Core Logic

The inputs A and B are first passed through individual NOT gates (made from tied-input NAND gates or standard NOT gates). The outputs become A and B.

These are then fed into a NAND gate. The final output Y is:

Y = A · B

Applying De-Morgan's Law:

Y = A + B

Y = A + B

This represents an OR operation.

Pattern Recognition

Bubbled inputs on a NAND gate convert it directly into an OR gate via De-Morgan's laws. (Bubbled NAND = OR).

Chapter Mix

Class 12 Physics: Semiconductor Electronics

More Semiconductors Questions — jee_main_2024_29_january_evening

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