Question:medium

The resultant gate and its Boolean expression in the given circuit is

Choose the correct answer from the options given below

Show Hint

An alternative shortcut is to build a quick truth table with boundary states: If $A=0, B=0 \rightarrow$ inverted inputs are $1, 1 \rightarrow$ NOR output is $0$. If $A=1, B=1 \rightarrow$ inverted inputs are $0, 0 \rightarrow$ NOR output is $1$. The output only goes high when both inputs are high, confirming it behaves exactly like an AND gate.
Updated On: Jun 12, 2026
  • NOR, $\overline{A + B}$
  • AND, $A \cdot B$
  • OR, $A + B$
  • NAND, $\overline{A \cdot B}$
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Read the circuit.
Inputs $A$ and $B$ are each passed through a NOT gate, and the two inverted outputs feed a NOR gate.
Step 2: Write the inverted inputs.
After the NOT gates the signals are $\overline{A}$ and $\overline{B}$.
Step 3: Apply the NOR operation.
A NOR gate outputs the complement of the sum of its inputs, so $Y = \overline{\overline{A} + \overline{B}}$.
Step 4: Use De Morgan's law.
The bar over a sum becomes a product of bars: $Y = \overline{\overline{A}}\cdot\overline{\overline{B}}$.
Step 5: Remove the double bars.
Since $\overline{\overline{A}} = A$ and $\overline{\overline{B}} = B$, we get $Y = A\cdot B$.
Step 6: Identify the gate.
The expression $A\cdot B$ is the AND function, so the resultant gate is AND, which is option (2).
\[ \boxed{\text{AND},\ Y = A\cdot B} \]
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