What are the uses of logic gates? Why is a NOT gate known as an inverter?

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USES OF LOGIC GATES: logic gates are the fundamental building blocks from which ALL digital circuits and digital systems are constructed -- by combining basic gates (NOT, OR, AND, NAND, NOR, X-OR) in different arrangements, engineers build up arithmetic and logic units, memory elements, decision-making and control circuitry, and ultimately entire digital devices such as calculators, computers, digital measuring instruments, and countless other pieces of modern digital electronics. Because NAND and NOR gates are each individually 'universal' (any other gate or digital function can be built from either one alone), a huge range of digital functionality can, in principle, be constructed from just one type of basic gate repeated many times over -- which is part of why gates like these are so central to how real digital hardware is actually manufactured. WHY THE NOT GATE IS CALLED AN INVERTER: the NOT gate has a single input and a single output, and its defining behaviour is to produce the exact logical OPPOSITE (negation) of whatever is applied to its input -- if the input is 0 (low), the output is 1 (high); if the input is 1 (high), the output is 0 (low). Because this action is precisely an 'inversion' of the input signal's logical state (flipping it to its oppo …

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Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2025Set ANNUAL1 markMCQ
$Q. The gate which produces high output, when its both inputs are high is -$
(a) X-OR gate
(b) AND gate
(c) NAND gate
(d) NOR gate
›Reveal solutionSolution

An AND gate's truth table gives a high (1) output only when every input is high.

For a two-input logic gate with inputs A, B: the AND gate follows $Y = A\cdot B$ , so $Y=1$ only when $A=1$ and $B=1$ (both inputs high); for any other input combination $Y=0$ . The OR-family and NAND/NOR gates behave differently — a NAND gate is high for every combination except both-high, and a NO …

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CBSE 2021Set A1 markMCQ
$Q. Which of the following is correct for fundamental gate? (A) AND, OR, NOT (B) AND,$
(OR)
$(C) NAND, NOR (D) OR, NOT$
›Reveal solutionSolution
The three fundamental logic gates are AND, OR and NOT.

Logic gates are the building blocks of digital circuits. The three fundamental (basic) gates are:

OR — output 1 if any input is 1 (logical addition, A+B),

AND — output 1 only if all inputs are 1 (logical multiplication, A·B),

NOT — inverts the input (Ā). …
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CBSE 2019Set ANNUAL1 mark
$Q. Mention one practical application of logic gates.$
›Reveal solutionSolution

Logic gates implement binary decision-making, so they form the core of every digital device, from calculators to computers to automated control systems.

Application

Logic gates (AND, OR, NOT, NAND, NOR, XOR) combine binary (0/1, HIGH/LOW) inputs according to Boolean rules. A practical example: in a digital calculator or computer, arithmetic and logical operations are built up entirely from networks of logic gates; another example is an automatic control circuit (e.g. a security/alarm system) that switches on an output only when a specific combination of input conditions ("sensor triggered" AND "system armed") is satisfied.

§ Honest curriculum note

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CBSE 2019Set ANNUAL1 mark
$Q. Name the logic gate which generates high output when at least one input is high.$
›Reveal solutionSolution

The logic gate that gives a high output if any one (or more) input is high is the OR gate.

…

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Q.What are the uses of logic gates? Why is a NOT gate known as an inverter?

Concept understanding — Logic Gates — NOT, OR and AND Gates

Q.What are the uses of logic gates? Why is a NOT gate known as an inverter?

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