Q.What is logic gate? Write down the truth table and Boolean expression for 'AND' gate.

[!TLDR] A logic gate is a one-output switching circuit following a fixed input-output logic rule; the AND gate's output is high only when every input is high, i.e. $Y=A\cdot B$. [!ANSWER] Logic gate: a digital circuit with one or more inputs, one output, whose output follows a defini …

A LOGIC GATE is a digital switching circuit having one or more input signals but only one output signal, whose output state is determined by a definite logical relationship to the states of its inputs. The AND GATE is a two-(or-more)-input, one-output gate representing logical multiplication: its output Y is HIGH (1) only when ALL of its inputs are simultaneously HIGH (1); if even one input is LOW (0), the output is LOW (0). For the standard two-input case, its truth table is: input A = 0, input B = 0 gives output Y = 0; A = 0, B = 1 gives Y = 0; A = 1, B = 0 gives Y = 0; and A = 1, B = 1 gives Y = 1 -- the output is high in exactly the one row where both inputs are high, and low in all three other rows. Its Boolean expression is $Y=A\cdot B$, where the $\cdot$ symbol denotes the logical AND operation -- directly analogous to ordinary multiplication, since multiplying 0s and 1s in the usual arithmetic sense reproduces this exact same table (0x0=0, 0x1=0, 1x …

Give the general logic-gate definition first, then specialise to the AND gate: state its defining rule (output high only if all inputs high), write out its t …

Confusing the AND gate's truth table with the OR gate's -- swapping which single row is the 'special' one (AND: only 1,1 gives 1; OR: only 0,0 gives 0) is a common s …