NOTE: Above figures include non-CSI data. last updated: Sept. 23, 2015 data sources. California Solar Statistics (CSS) is the official public reporting site of the California Solar Initiative (CSI), presented jointly by the CSI Program Administrators and the California Public Utilities Commission.
Sound can travel through air, water, or solids, but it can't travel through a vacuum. It needs the medium to help it travel. Other examples include water waves, seismic waves, and waves traveling through a spring. Electromagnetic waves are waves that can travel through a vacuum (empty space). They don't need a medium or matter. They travel through electrical and magnetic fields that are generated by charged particles. Examples of electromagnetic waves include light, microwaves, radio waves, and X-rays.
Electromagnetic waves: 1. Electromagnetic (EM) waves (example light waves, radio waves, x-rays etc) can travel through vacuum; they do not require any medium (matter) to travel through and their travel is reduced, to some extent, by the presence of any medium. The common examples of medium are glass, water, air etc.