Boolean Logic
Overview
Deep inside every processor, decisions are made by tiny circuits that know only true and false, 1 and 0. These are logic gates, and by wiring them together a computer can add, compare and choose. Learn the handful of gates and you can read the logic of any digital circuit and predict exactly what it will output.
In this lesson you will recognise the standard symbol for each gate, learn precisely when each one outputs a 1, and then move between the three ways of describing logic: a problem in words, a logic expression, and a truth table. You will build a circuit, complete its truth table, and write the matching expression.
Objectives
- 1 Identify and use the standard symbols for logic gates
- 2 Define and understand the functions of logic gates
- 3 (a) Use logic gates to create given logic circuits from a: (i) problem statement (ii) logic expression (iii) truth table (b) Complete a truth table from a: (i) problem statement (ii) logic expression (iii) logic circuit (c) Write a logic expression from a: (i) problem statement (ii) logic circuit (iii) truth table
Audio Lesson
Listen to this lesson in the app
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Boolean Logic. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which gate outputs 1 only when both inputs are 1? A. OR B. AND C. NOR D. XOR Answer: B
- Which gate outputs 1 only when the two inputs are different? A. AND B. NAND C. XOR D. NOR Answer: C
- A NOR gate outputs 1 when: A. both inputs are 1 B. either input is 1 C. both inputs are 0 D. the inputs differ Answer: C
- The logic expression A.B represents which gate? A. OR B. AND C. NOT D. XOR Answer: B
- How many rows are needed in a truth table for a circuit with two inputs? A. 2 B. 3 C. 4 D. 8 Answer: C
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on Boolean Logic? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
