Chemistry
How to draw dot and cross diagrams for covalent bonds
To draw a dot and cross diagram for a covalent bond, show the outer electrons only: dots for one atom, crosses for the atoms it bonds to. ...
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Maths
How to solve simultaneous equations: chickens and rabbits
Simultaneous equations are two equations that are true at the same time. To solve them by elimination, make the number in front of one let...
System Design
Event-Driven Architecture Explained With a Python Example
Event-driven architecture is a way of building software where a part of the system announces what just happened, such as "order place...
Builds
AND gate and OR gate using transistors: build both
To make an AND gate using transistors (switches flipped by electricity), put two in a row. Current must pass through both, so an LED wired...