• Why is the Earth like a magnet?
  As the Earth spins, the swirling of its iron core turns the core into ...

• How do CT scans work?
  CT (computed tomography) scans run X-ray beams right round the body, ...

• What is resonance?
  If allowed to vibrate freely, every object always tends to vibrate at ...

• How do TV signals travel?
  TV signals travel in one of three ways. Terrestrial broadcasts are ...

• What is sound frequency?
  Some sounds, like a car's squealing brakes, are very high-pitched. ...

• Who made the first radio broadcast?
  Italian inventor Guglielmo Marconi first sent radio signals over 1.6 ...

• What is an echo?
  An echo is when you shout in a large empty hall or in a tunnel, and ...

• What is an electric current?
  A current is a continuous stream of electrical charge. It happens ...

• What is a silicon chip?
  A silicon chip is an electronic circuit implanted in a small crystal ...

• How do electric currents flow?
  The charge in an electric current is electrons that have broken free ...