AMONG the facts to be explained in a satisfactory theory of the propagation of radio waves over the earth's surface are the curvature of the rays in transmission between stations far apart ...

So, instead of using ultrasound, radio waves are used as they travel at 300,000,000 m/s. It works in the same way as sonar but with radio waves in place of ultrasound. A short pulse of radio waves ...

electromagnetic waves, radio waves, microwaves, infrared and visible light and ultraviolet, EM waves in medicine and ionising radiation. If you struggled with the quiz, don't panic - we've got you!

The systematic investigation of the properties and characteristics of these very short waves was taken up in view of the advantages which they seemed to offer in the field of practical radio ...