JEE Physics 2025 Question with Solution

Given: The digital logic circuit has both inputs equal to $1$.

Find: The values of $P$ and $Q$.

From the solution, the gate operations are evaluated step by step.

The top-left gate is a NAND gate with inputs $1$ and $1$. Therefore,

and hence,

This output $0$ is sent to the lower-left OR section and also to the rightmost AND gate.

The lower-left OR gate receives inputs $1$ and $0$. So,

This then passes through a NOT gate, giving

The NOR gate for $Q$ receives inputs $1$ and $0$. Therefore,

and so,

For $P$, the rightmost AND gate receives inputs $1$ and $0$. Thus,

Therefore, the outputs are $P = 0$ and $Q = 0$.

The solution explicitly concludes that the correct option is B and also states $(2)\; P = 0, Q = 0$. Since the listed options are shifted in the provided input, the value-based correct answer corresponds to the first available option text.

Given: Both inputs are HIGH, i.e. $1$ and $1$.

Find: Output values of $P$ and $Q$.

1. First evaluate the NAND gate:

2. Feed this $0$ into the lower OR branch along with direct input $1$:

3. Invert this output using the NOT gate:

4. Send this $0$ and direct input $1$ to the NOR gate:

so

Hence $Q = 0$. 5. For the top-right AND gate:

Hence $P = 0$.

So the final output is $P = 0, Q = 0$.