Milka's use of this image is NOT acceptable!. The advice I would give her is to next time site the wedsite so she does not plagiarize and get in trouble.
lenses produce their image due to reflection of light
The drawing technique of using dots instead of lines called stippling. Using lines instead of dots on the other hand is called hatching. Stippling involves placing individual dots across a surface in a pattern that will be identifiable. Individual dots are used to imply the shape, texture, or shadowing of a subject.
