How does a magnifying glass work?
A magnifying glass makes the print on this page look much bigger than it is.
A magnifying glass is a glass lens that is thicker in the middle than it is on the edges. It makes close objects look bigger because of the way in which it bends the rays of light that pass through it.
Light rays travel through the air in a straight line. When you look through a glass windowpane, you see everything through it as it is. The glass windowpane is flat, it does not bend or change the direction of the light rays.
But the glass in a magnifying lens is curved. When you hold a magnifying glass close to a page, the curved lens bends and spread the light, so that the words you are reading look bigger than they really are.
Not all lenses make things look bigger. Some lenses are thicker at the edges than they are in the middle. They bend the light rays in such a way that the image is always smaller than the object. – Dick Rogers