The symbols and truth tables of the AND, OR, NOT, NAND and NOR gates, analysing circuits of up to three gates, simple alarm circuits, and the impact of electronics on society.
6 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
A burglar alarm should sound only if the system is armed AND a door opens. That “AND” is a logic gate.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
1 = high voltage; 0 = low voltage.
Q = 1 only if both inputs are 1.
Q = 1 if either or both inputs are 1.
One input; Q is the opposite.
NOT AND: Q = 0 only if both inputs are 1.
NOT OR: Q = 1 only if both inputs are 0.
Find the output of each gate in turn; build the truth table with all combinations.
Give benefits and drawbacks of electronics.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (11 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [11 marks]
An alarm uses an AND gate with inputs A (door sensor, 1 = door open) and B (armed switch, 1 = armed). The output Q sounds the buzzer when Q = 1.
(a) (a) Draw the symbol for an AND gate and label the inputs and output. [2]
(b) (b) Complete the truth table for the AND gate. [2]
(c) (c) State when the buzzer sounds. [1]
(d) (d) The output of the AND gate is now connected to one input of an OR gate whose other input C is a panic button. State the output Q when A = 0, B = 1, C = 1. [2]
(e) (e) Describe the difference between a NOR gate and an OR gate. [2]
(f) (f) Give one advantage and one disadvantage of the use of electronic technology in society. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.