Everyday wonders

How a magnet, a coil of wire and a paper-thin dome turn your phone's music into sound, and how noise cancelling silences a roaring danfo.

How a fridge pumps heat out of the box, why the coils at the back feel warm, and what happens to your stew when the power goes off.

How five tiny pins, five springs and one line you cannot see let only the right key turn a lock.

How a magnetron, a metal box and billions of spinning water molecules warm up last night's jollof in two minutes.

How a floating ball, a rubber flap and a siphon in the bowl flush a toilet, and how Cape Town learned to save every litre.

How a lens, a hole that can shrink and a shutter that blinks catch a portrait on film, in a photo studio in Bamako.

What is inside the phone in your pocket: a sandwich of glass, a lithium battery, a chip with billions of switches, cameras, antennas and a tiny buzzing motor.

How a needle, a spinning hook and a little bobbin tie two threads together hundreds of times a minute: the lockstitch.

How pressing a key throws a felt hammer at a steel string, lets go just in time, and stops the sound when you lift your finger.

How a front-loading washer fills, tumbles, drains and spins your clothes nearly dry, with water that only ever travels through valves, hoses and a pump.

How a split air conditioner picks heat up in your bedroom, carries it through the wall in copper pipes and throws it out into the street.

How a tiny rolling ball, a tube of thick ink, gravity and two small holes let you write for hours in an exam hall.

How two rows of tiny hooked teeth and one Y-shaped slider close a bag in a second and hold it shut all day.

How a printer steps paper past a head that sweeps to and fro, firing millions of tiny drops of four inks to build words and pictures out of dots.

How a kettle turns electricity into heat, knows when its water boils and clicks itself off, high up in Addis Ababa where water boils at about 92 °C.

How a chain, a stack of sprockets and a little sprung arm let one pair of legs race on the flat and still climb Rwanda's steepest hills.

How a sheet of glass knows exactly where your finger is: a grid of see-through wires, a tiny charge at every crossing and a chip that checks them all over a hundred times a second.

How sunlight on a silicon panel pushes electrons through wires into a battery, and how that stored sunshine lights a bulb after dark.

How a crash sensor, a tiny explosion and a nylon bag catch a driver in less time than it takes to blink.

How a pump, two copper boilers and nine bars of pressure squeeze a shot of espresso out of a puck of Ethiopian coffee.