Question

The output of a 2-input OR gate is zero only when its
(A) both inputs are 0
(B) either input is 1
(C) both inputs are 1
(D) either input is 0

Answer 1

Hint: We know that logic gates are the basic building blocks of any digital system. It is an electronic circuit having one or more than one input and only one output. The relationship between the input and the output is based on a certain logic. Based on this, logic gates are named as AND gate, OR gate, NOT gate etc. Logic gates perform basic logical functions and are the fundamental building blocks of digital integrated circuits. Most logic gates take an input of two binary values, and output a single value of a 1 or 0. Some circuits may have only a few logic gates, while others, such as microprocessors, may have millions of them.

Complete step by step answer
We know that the symbol is an OR gate with a small circle on the output. The small circle represents inversion. The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high. Wherever the occurrence of any one or more than one event is needed to be detected or some actions are to be taken after their occurrence, in all those cases OR gates can be used.
It can be said that when a transistor is on, or open, then an electric current can flow through. When you string a bunch of these transistors together, then you get what's called a logic gate, which lets you add, subtract, multiply, and divide binary numbers in any way imaginable. In a physical circuit, these logic gates have: Inputs.
The truth table for 2-input OR gate is as shown in the figure which is given below:

Input 1	Input 2	Output
0	0	0
0	1	1
1	0	1
1	1	1

Thus, the output is zero only when both inputs are zero.
Hence the correct answer is option A.

Note: Thus, it can be said that digital systems are said to be constructed by using logic gates. These gates are the AND, OR, NOT, NAND, NOR, XOR and XNOR gates. The basic operations are described below with the aid of truth tables. AND gate The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are high. Boolean logic is a very easy way to figure out the truth of an expression using the simple concept of true or false. In a nutshell, Boolean logic means you are working with stuff that is either TRUE or FALSE. But as we can construct other logic switching functions using just these gates on their own, they are both called a minimal set of gates. Thus, the NAND and the NOR gates are commonly referred to as Universal Logic Gates.