Electromagntic wave, such as an X-ray.
Explanation:
- Electromagnetic wave does not require any medium to travel. These waves propagate outwards from the source.
- They can travel even through the vacuum of outer space.
- The major source is the sun which emits radiation in the form of the Electromagnetic spectrum.
- These waves travel through oscillating electrical and magnetic fields generated by the oscillating charged particles.
- These waves oscillate in the perpendicular direction of planes concerning each other and are in form.
- Electromagnetic waves travel at speed of light.
Hoyts theory of urban land use and development emerged in response to changes in TRANSPORTATION
Canals and inland waterways, natural or artificial waterways used for ... The lay of the land (topography) and particularly changes in water levels ... inland waterway transport is still more economical than any other kind of transport.
4. The Roman Empire
( Muslim Empire is not a thing)