Question

Switch $S$ is used to short circuit the bulb.


The logic gate realized from the above electrical circuit is :

• A. $\text{NOR}$
• B. $\text{NOT}$
• C. $\text{OR}$
• D. $\text{AND}$

Answer 1

The correct option is B $\text{NOT}$

If the switch is open, the bulb is not short-circuited and the bulb will be in $ON$ position ( The current will flow in circuit ).

In terms of logic function,

If $A=0$ (Switch open), then $B=1$ (Bulb is ON)

If $A=1$ (Switch closed), then $B=0$ (Bulb is Off)

$\Rightarrow B=\overline{A}$.

Therefore, the circuit represent a $\text{NOT}$ gate.

Hence, option $\left(B\right)$ is correct.

Why this question? It intends to test your understanding of binary system in real application. Tip : To depict every phenomenon in binary system, concentrate on the fact that everything has to be assigned values in terms of Yes $\left(1\right)$ or No $\left(0\right)$ / High value $\left(1\right)$ or Low value $\left(0\right)$.