Logic Gates & Boolean Algebra — A/L Physics

Logic Gate A digital electronic circuit that performs a Boolean function on one or more binary inputs to produce a single binary output. Logic gates are the fundamental building blocks of digital systems, from calculators to microprocessors. Each gate implements a specific logical operation (AND, OR, NOT, etc.) using transistors operating in saturation or cut-off regions. For example, an AND gate in a security system might require both a keycard scan and a PIN entry to unlock a door.

Truth Table A tabular representation of all possible input combinations and their corresponding output for a given logic gate or circuit. For n inputs, the truth table has 2ⁿ rows. The output column is determined by the gate’s Boolean function. For instance, a 2-input OR gate has 4 rows: (0,0)→0, (0,1)→1, (1,0)→1, (1,1)→1. Truth tables are essential for verifying circuit behaviour and deriving Boolean expressions.