Question

Which of the following symbols represents a Universal gate?

Answer 1

Hint: A universal gate can implement any Boolean function without need to use any other type of gate. NAND and NOR gates are the universal gates.

Complete step by step answer:
A universal gate is a logic gate that can be used to construct all the other types of logic gates. NAND and NOR gates are widely known as universal logic gates. It means that any other logic gate can be made using a NAND or NOR gate.

A NAND gate (NOT-AND) is a type of logic gate which produces an output whose value is false only when all inputs are true. NAND is the complement of AND gate. The NAND Boolean function has a property of functional completeness. It means that any Boolean expression can be re-expressed using a NAND gate only.

Representation of a NAND gate:

NAND gate is a universal gate.Hence, the correct option is B.
Additional information:The disadvantage of using complete sets of AND, NOT and OR gates is that we require two or more of different types of logic gates to produce any equivalent logic gate. Therefore, we use NAND or NOR gates to satisfy all Boolean functions and gates by using just one single type of universal gate. NOR gate also functions as a universal gate. It gives a positive output only when both the inputs are negative. NOR gate can be expressed as the complement of OR gate.

Note :NOR and NAND gates can be combined to form any other type of logic gate. By using the universal gates, we create a range of other Boolean functions and gates.Students need to remember the symbols of all logic gates to choose the right option.