Description

• An MRI machine combines a strong electromagnet, a radio transmitter, and a computer. The magnet forces molecules to line up, radio waves probe the body, and the computer makes the images.
  
  

Magnet

• MRIs have some of the most powerful electromagnets in common use. Their magnetic field strength is 3 teslas, about 100,000 times stronger than the Earth's.
  
  

Superconductor

• The secret behind the electromagnet's strength is the superconducting wire. The magnet is immersed in liquid helium at --269C and has no electrical resistance.
  
  

Current

• Since the magnet has no resistance, it needs only an initial jolt of electricity. As long as the magnet stays cold, the same current will flow in it forever.
  
  

History

• Scientific development of MRI took place during the 1970s based on theoretical work done in the 1940s. The first commercial MRI was made in 1980.