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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 corresponding to the circuit given below is:
Logic gate circuit diagram for Q13 - JEE Main 2025 Evening
Diagram showing a combination of logic gates connected to inputs A and B resulting in output C.

Solution & Explanation

Related Formula

Boolean operators for basic logic gates:

  • OR gate:
  • Y = A + B

  • AND gate:
  • Y = A · B

Core Logic

Analyze the schematic:

  • Input lines A and B are linked into an OR gate, yielding output:
  • Y = A + B

  • This term A + B and the original input line A form the inputs to a final AND gate.
  • The final output expression C is therefore:
C = A · (A + B)

Logic Gates and Truth Tables
Diagram showing a combination of logic gates connected to inputs A and B resulting in output C.

Step 1: Construct the Truth Table

Compute output values for each input combination:

  • For A=0, B=0:
C = 0 · (0 + 0) = 0
  • For A=1, B=0:
C = 1 · (1 + 0) = 1 · 1 = 1
  • For A=0, B=1:
C = 0 · (0 + 1) = 0 · 1 = 0
  • For A=1, B=1:
C = 1 · (1 + 1) = 1 · 1 = 1

This matches Table 2.

Pattern Recognition

Using Boolean algebra:

C = A · (A + B) = A · A + A · B = A + A · B

By absorption law:

A + A · B = A

So the circuit is equivalent to a simple buffer carrying input A. The output C must match input A under all conditions. Checking the options, Table 2 is the one where output C tracks input A directly (0, 1, 0, 1).

Chapter Mix

Class 12 Physics: Semiconductors

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_2025_03_april_evening

Practice all Semiconductors previous-year questions →

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