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// EXPLAINED SIMPLY · a→Z

Explained Simply

Big Ideas, Made Simple — Big, mind-blowing tech ideas (GPS, Wi-Fi, memory, computers) explained so simply that anyone gets it in 30 seconds.

0 of 12 lessons out · next: What is electricity, really?

  1. 02 PLANNEDHow does a computer think with just ON and OFF?Billions of transistor switches form logic gates; gates add binary numbers, and everything a computer does is built from that.
  2. 03 PLANNEDHow does GPS know where you are?Your phone times signals from 4+ satellites; distance = time × light speed, and the satellite clocks are corrected for relativity (about 38 microseconds a day).
  3. 04 PLANNEDHow does Wi-Fi send a video through the air?Radio waves at 2.4 / 5 GHz; changing the wave's strength and timing (phase) encodes the 1s and 0s of your video.
  4. 05 PLANNEDHow does your phone remember things with the power off?Flash memory traps electrons in a tiny insulated cell; trapped = 0, empty = 1, and they stay for years without power.
  5. 06 PLANNEDHow does a solar panel turn light into electricity?Light knocks electrons loose at the P-N junction inside the silicon; the junction pushes them one way = a current.
  6. 07 PLANNEDHow does a CPU do billions of things a second?A clock ticks billions of times a second (GHz); on every tick the transistors take one tiny step.
  7. 08 PLANNEDHow does a speaker turn electricity into sound?Current in a coil next to a magnet pushes a cone back and forth; the cone pushes the air = sound.
  8. 09 PLANNEDHow does internet travel through glass?Fibre optics: light pulses bounce along a glass thread (total internal reflection) at about two-thirds of light speed.
  9. 10 PLANNEDWhat is a semiconductor, really?A material between a conductor and an insulator; adding a tiny bit of another element (doping) controls how it conducts.
  10. 11 PLANNEDHow does a QR code hold a link?Black and white squares are bits; built-in error correction lets the code still work with up to about 30 % of it damaged.
  11. 12 PLANNEDWhy do electric cars accelerate so fast?An electric motor gives full twisting force (torque) from zero speed, with no gearbox to shift.