Find the correct combination of A, B, C and D | vedclass

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(D) The $LED$ glows when it is forward biased, meaning the potential at point $P$ must be high $(1)$ and the potential at point $Q$ must be low $(0)$.

Vedclass · Accepted Answer

$1101$

Vedclass · Answer

(D) The $LED$ glows when it is forward biased, meaning the potential at point $P$ must be high $(1)$ and the potential at point $Q$ must be low $(0)$.Let the output of the first $NOR$ gate be $Y_1 = \overline{A+A} = \overline{A}$ and the second $NOR$ gate be $Y_2 = \overline{B+B} = \overline{B}$.The output at $P$ is the output of a $NAND$ gate: $P = \overline{Y_1 \cdot Y_2} = \overline{\overline{A} \cdot \overline{B}} = A + B$.For $P = 1$, we need $A+B = 1$, which means at least one of $A$ or $B$ must be $1$.The output at $Q$ is the output of a $NOR$ gate: $Q = \overline{C+D}$.For $Q = 0$, we need $\overline{C+D} = 0$, which implies $C+D = 1$, meaning at least one of $C$ or $D$ must be $1$.Checking the options:$A) 0100: A=0, B=1, C=0, D=0 \implies P=1, Q=1$ (No glow)$B) 0011: A=0, B=0, C=1, D=1 \implies P=0, Q=0$ (No glow)$C) 1000: A=1, B=0, C=0, D=0 \implies P=1, Q=1$ (No glow)$D) 1101: A=1, B=1, C=0, D=1 \implies P=1, Q=0$ ($LED$ glows).Thus, the correct combination is $1101$.

Find the correct combination of $A, B, C$ and $D$ inputs which can cause the $LED$ to glow.

Similar Questions

Which logic gate is represented by the following truth table?

$A$ $B$ $Y$

$0$ $0$ $1$

$0$ $1$ $0$

$1$ $0$ $0$

$1$ $1$ $1$

Identify the logic gate represented by the given circuit.

The logic gate combination shown in the figure represents which of the following gates?

Identify the logic gate from the following with the same truth table characteristics as the logic circuit shown below.

The truth table for the system of four $NAND$ gates as shown in the figure is:

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