The Magnifier
The magnifying glass is one of the oldest and simplest optical devices.
Thousands of years ago, the Egyptians used small pieces of crystal or obsidian (a type of shiny stone) to better see small objects.
The first magnifying glass built for scientific purposes is believed to have been designed by the English philosopher Roger Bacon in 1250. He was a lecturer at the University of Oxford. Bacon carried out various experiments with magnifying glasses and mirrors and described the principles of reflection and refraction.
A magnifying glass, also known as a handheld lens, is a convergent (convex) lens that is used to magnify the image of an object.
The magnification of the magnifier is given by the optical power (P) and is given by the convergence of the magnifier.
α2 = the angle at which the object is seen through the magnifying glass y1 = the size of the
object
Since the object is very close to the focus, tg α2 ≈ y1/f.
