The Force Behind Electronics
All of electronics — and thus all of computing hardware — rests on electric charge. Charge comes in two signs, positive and negative, carried by protons and electrons. The fundamental rule: like charges repel, opposite charges attract. Charge is conserved (never created or destroyed, only moved) and quantized (it comes in whole multiples of the elementary charge ).
The force between two point charges is Coulomb's law: proportional to the product of the charges and inversely proportional to the square of the distance. This inverse-square form means the force weakens rapidly with separation — doubling the distance quarters the force. It is strikingly similar in form to gravity, but electric forces are vastly stronger and can both attract and repel.
Rather than think of charges reaching across empty space, physics uses the electric field : a charge creates a field in the space around it, and another charge placed there feels a force . The field is the force per unit charge, pointing away from positive charges and toward negative ones. This "field" idea — a quantity defined at every point of space — is one of physics' most important abstractions and returns in electromagnetism and, ultimately, light.
Voltage (electric potential) is the potential energy per unit charge — the "electrical height" that drives charges to move. A charge moves from high to low potential just as a ball rolls downhill, and the voltage difference between two points is what pushes current through a circuit (next lesson). Voltage is why a battery can do work on charges.
Common pitfall: getting the sign of the force wrong (like charges repel, opposites attract — not the reverse), and forgetting the inverse-square distance dependence. Coulomb's force falls off as , so it drops fast with distance — doubling the separation cuts the force to a quarter, not a half. And two positive (or two negative) charges push apart; attraction requires opposite signs.