Mechanical waves require a medium to travel through. Examples of mechanical waves are sound waves, water waves, a vibrating string. (See related link). Electromagnetic waves â¦(such as light, radio waves, X-rays, microwaves) do not need a medium to travel through, so these are not mechanical waves.
Photostat definition, a camera for making facsimile copies of documents, drawings, etc., in the form of paper negatives on which the positions of lines, objects, etc., in the originals are maintained. a copy made with this camera.
Zyl (zylonite, acetate or Cellulose acetate) is a material that is a very cost-effective and creative option for eyewear. It is a sturdy, lightweight, moldable material that can be made in a variety of colors and shapes. Zyl eyeglass frames are the most prominent of the plastic eyeglass frames in use today.