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Why is a rainbow curved? Why does a magnet stick to the fridge but not to wood? Short, sourced, clear articles.
NewestTechnology and Engineering
A processor takes billions of steps a second, yet it spends much of its time waiting for data. We explain the fetch-decode-execute cycle, the clock signal, registers and the layers of memory from cache to disk, with a workshop drawing where you can type in your own numbers.
Kuazara Bilim Ekibi11 min read
A factory robot arm brings its gripper to a point by turning six joints. Using an arm you can play with, we explain what a joint is, why there are exactly six (degrees of freedom) and how to work out where the gripper is from the joint angles (forward kinematics).
10 min read
From toy cars to windscreen wipers, small direct current motors turn everywhere. Using a motor you can play with, we explain the force a magnet puts on a current-carrying wire, the clever switch the commutator makes every half turn, and how voltage, speed, torque and back EMF are linked.
11 min read
In 1831 Michael Faraday pushed a magnet into a reel wound with copper wire and the galvanometer needle moved; when the magnet stopped, the needle went back to zero. We explain how changing magnetic flux drives a current, the law ε = −N·dΦ/dt, Lenz's law, generators and transformers.
13 min read
Between 1909 and 1913 Robert Millikan measured the charge of the electron by watching micron-sized oil drops float between two metal plates through a microscope. We explain the apparatus, Stokes' law, the qE = mg balance and why every charge came out as a whole multiple of e.
10 min read
In 1909 Geiger and Marsden fired alpha particles at thin metal foils; most went straight through, but a few bounced back. We explain Thomson's plum pudding model, the apparatus, Rutherford's nuclear model and the 1/sin⁴(θ/2) scattering formula with a simulation.
10 min read
In 1851 a 28-kilogram ball was hung on a 67-metre wire from the dome of the Panthéon in Paris. As the hours passed, its plane of swing slowly turned against the floor. We explain why it turns, why the rate depends on latitude, and how long a full turn takes in Istanbul and Ankara.
9 min read
Light passing through two thin slits leaves bright and dark bands on a screen. We explain the idea of interference Thomas Young put forward in 1801, the fringe-spacing formula, experiments with single photons and electrons, and why the pattern disappears when we measure "which slit" was used.
11 min read
Why can bright red light fail to free a single electron from a metal, while dim violet light frees them at once? From Hertz to Einstein and Millikan, we explain the photoelectric effect, the threshold frequency and the stopping voltage with a worked example.
13 min read
We shift to an easy gear to ride a bike up a hill and to first gear to pull away in a car. A gearbox makes no power; it shares the motor's power between speed and torque. We explain gear ratios, the torque × speed balance and what happens inside when you change gear, with a gearbox to play with.
10 min read
The dark blue panel on a roof makes electricity without moving at all. We explain how a photon creates an electron–hole pair in silicon, how the p-n junction separates the pair, why half-volt cells are connected in series, and how the angle and the shadow of a single leaf change the power.
11 min read
How can a hand lever lift a hundred-kilogram load? We explain what pressure is, why a confined liquid passes pressure on equally in every direction, how a small and a large piston multiply force, and the price you pay for it: distance, worked out step by step.
9 min read