Free NEET Physics multiple-choice questions on Logic Gates. Attempt each question and reveal the answer with a full explanation.
The logic gate that performs the function of 'Inversion' is: NOT gate OR gate AND gate XOR gate The Boolean expression A + B is equivalent to: A B A + B A B A + B A logic gate which gives an output 'high' only when all its inputs are 'high' is: AND gate OR gate NAND gate NOR gate A 3-input NOR gate gives a 'High' output (1) only when: All inputs are 0 Any one input is 1 All inputs are 1 Two inputs are 0 and one is 1 The logic gate XNOR is also known as the: Equivalence gate Anti-coincidence gate Sum gate Inhibit gate Which of the following describes a 'Buffer' logic gate? The output is always equal to the input The output is the inverse of the input The output is 1 only if all inputs are 0 The output is 0 only if all inputs are 1 What is the decimal equivalent of the largest 4-bit binary number? 15 16 7 31 For a logic circuit with output Y = (A+B) C , what is the output when A=1, B=0, C=1 ? 0 1 Undefined Depends on previous state Which of the following is the truth table for the XOR gate? Inputs: (0,0)->0, (0,1)->1, (1,0)->1, (1,1)->0 Inputs: (0,0)->0, (0,1)->0, (1,0)->0, (1,1)->1 Inputs: (0,0)->1, (0,1)->0, (1,0)->0, (1,1)->0 Inputs: (0,0)->0, (0,1)->1, (1,0)->1, (1,1)->1 A logic gate is represented by the expression Y = A ⋅ B . This gate is: NAND NOR AND NOT Identify the logic gate represented by the following truth table: | A | B | Y | |---|---|---| | 0 | 0 | 1 | | 0 | 1 | 1 | | 1 | 0 | 1 | | 1 | 1 | 0 | NAND NOR AND XOR Which logic gate is used to detect if two binary bits are different? XOR AND OR NAND Which gate is represented by the following Boolean identity: Y = A + B ? OR gate AND gate NOT gate NAND gate Identify the universal logic gate from the following: NOR AND OR NOT What is the Boolean expression for a logic circuit consisting of an OR gate followed by a NOT gate? A + B A B A + B A + B The logic gate whose output is 'Low' only when all its inputs are 'High' is: NAND AND NOR OR Which of the following gates is called a Universal Gate? NAND OR AND XOR Which of the following is the correct truth table for a 2-input NAND gate? A=0, B=0, Y=1; A=0, B=1, Y=1; A=1, B=0, Y=1; A=1, B=1, Y=0 A=0, B=0, Y=0; A=0, B=1, Y=0; A=1, B=0, Y=0; A=1, B=1, Y=1 A=0, B=0, Y=1; A=0, B=1, Y=0; A=1, B=0, Y=0; A=1, B=1, Y=0 A=0, B=0, Y=0; A=0, B=1, Y=1; A=1, B=0, Y=1; A=1, B=1, Y=1 The decimal equivalent of the binary number (1101) 2 is: 13 11 14 15 The output of a 2-input NOR gate is high only when: Both inputs are low One input is high and the other is low Both inputs are high Any one input is low What is the Boolean expression for the logic circuit representing a NAND gate whose inputs are tied together? A A 1 0 A logic gate has inputs A=1, B=1 and output Y=0 . Which gate can it NOT be? AND NAND NOR XOR The figure shows a logic circuit with two inputs A and B and the output C. The voltage waveforms of A, B and C are as shown. The logic gate is: AND gate OR gate NAND gate XOR gate A digital circuit which has two inputs A and B and produces an output Y = A B + A B is: XOR gate XNOR gate NAND gate OR gate Which logic gate is equivalent to the following circuit? (Inputs A and B are connected to a NOR gate, the output of which is connected to a NOT gate). OR AND NAND NOR Which of the following Boolean expressions represents the logic gate that gives a 'Low' output only when both inputs are 'High'? Y = A B Y = A + B Y = A B Y = A + B The output of a NAND gate is 0 only when: Both inputs are 1 Both inputs are 0 Any one input is 0 Any one input is 1 In the following logic circuit, if A=0 and B=1 , the output Y is: 0 1 High impedance Cannot be determined The output Y of the following gate circuit is given by: Y = A B + C Y = (A+B) C Y = A B C Y = A+B + C The symbolic representation of a logic gate is shown. This gate is: NOR OR NAND NOT In the Truth Table of an XOR gate, the output is '1' when: The inputs are different Both inputs are '1' Both inputs are '0' The inputs are same What is the output Y in the following circuit, when all three inputs A, B, C are first 0 and then 1 ? 1, 0 0, 1 1, 1 0, 0 For the logic circuit shown, the output Y is: A B A + B A B A+B Which of the following logic gates is equivalent to a series combination of two switches? AND gate OR gate NOR gate NAND gate The circuit diagram shows a logic combination. The output Y is: A + B A+B A B A B Which of the following logic gates provides a high output (1) when both inputs are low (0) and a low output (0) when both inputs are high (1)? NOR AND OR XOR The logic circuit equivalent to a single gate is: AND OR NAND XOR The output Y of the logic circuit shown below is: A − B A ⋅ B A + B A What is the Boolean expression for the output Y of the following logic circuit? A + B A B A + B A + B De Morgan's first law is represented by: A + B = A ⋅ B A ⋅ B = A + B A = A A + AB = A The output of an OR gate is connected to both inputs of a NAND gate. This combination will work as a: NOR gate AND gate OR gate NAND gate The output of the logic circuit shown below is 1 when the inputs A and B are: A=1, B=0 A=0, B=0 A=0, B=1 None of these For a logic circuit with two inputs A and B , the output Y is given by Y = A B (A + B) . What is the output Y when A=1 and B=1 ? 0 1 Undefined None of these Identify the logic gate that corresponds to the Boolean expression Y = A B + A B . XNOR XOR NAND NOR What is the Boolean expression for a 'Half-Adder' circuit producing the 'Sum' bit S from inputs A and B ? S = A B S = A B S = A + B S = A B In the timing diagram for a logic gate, inputs A and B are as follows: A is High for t 1 to t 2 , and B is High for t 2 to t 3 . If the output Y is High only from t 1 to t 3 , the gate is: OR AND XOR NAND What is the Boolean simplification of (A + B) (A + B ) ? A B A+B 0 If a logic circuit output is given by Y = A + B + A B , what is the value of Y for A=0, B=1 ? 1 0 Cannot be determined None of these The logic circuit shown below has three inputs A, B and C . To get an output Y = 1 , the inputs must be: A = 1, B = 0, C = 1 A = 1, B = 0, C = 0 A = 0, B = 1, C = 0 A = 1, B = 1, C = 0 The logic gate circuit which corresponds to the Boolean expression Y = A + B is equivalent to which single gate? NAND NOR AND OR How many NAND gates are required to implement a basic OR gate? 3 2 4 1 A logic gate has three inputs A, B, C . The output is 1 only when A=1, B=0, C=1 . Which of the following Boolean expressions represents this gate? Y = A B C Y = A + B + C Y = A B C Y = A B C How many NOR gates are required to produce an AND gate? 3 2 4 1 The output of the logic gate combination shown in the figure is: A B + A B A B + A B A B A + B What is the Boolean expression for the output Y in the following circuit? Y = A B C Y = A + B + C Y = (A+B) C Y = A B C For a logic gate with inputs A and B , the output is Y = A (A + B) . This is equivalent to which gate? NOT AND OR NAND To get an output Y=1 from the circuit shown below, the input must be: A=1, B=0, C=1 A=0, B=1, C=0 A=1, B=1, C=0 A=0, B=0, C=1 How many 2-input NAND gates are required to implement a 2-input XOR gate? 4 3 5 2 What is the Boolean expression for the output Y of a logic circuit consisting of two NAND gates where the output of the first is fed into both inputs of the second? Y = A B Y = A + B Y = A B Y = A + B The logic operation performed by the circuit shown below is equivalent to: AND gate OR gate NOR gate NAND gate The Boolean expression A B + A reduces to: 1 A B B Which of the following circuits correctly represents the logic gate that follows the Boolean identity Y = A+B using only NAND gates? A NAND gate followed by another NAND gate acting as a NOT gate Two NOT gates (NAND with inputs tied) followed by a NAND gate A NAND gate with inputs A and B Three NAND gates connected in parallel What is the Boolean expression for the output Y of the logic circuit where inputs A and B are passed through a NOR gate, and the result is NANDed with input A ? Y = (A+B) A Y = A+B + A Y = A B + A Y = A B Which of the following is the correct truth table for the logic gate circuit where two NOR gates are cross-coupled (SR Latch)? Output depends on previous state Output is always 1 Output is always 0 Output is XOR of inputs What is the output Y of the Boolean function Y = A B + A B + A B ? A + B A B 1 0 A logic circuit has the Boolean output Y = A B + A B . This corresponds to which logic gate? XOR XNOR AND NOR Which gate is known as a 'coincidence gate' because it produces a high output only when all its inputs are at the same high logic level? AND OR NOT XOR The binary representation of the decimal number 25 is: 11001 11011 10101 10011