Use of Convex Lenses and Concave Mirrors

Convex Lenses

Convex lenses, also known as converging lenses, are curved outwards on both sides.
When parallel light rays pass through a convex lens, they converge at a single point, known as the focus.
The focal length of a lens is the distance from the centre of the lens to the focal point.
The magnification provided by a lens is the ratio of the image size to the object size. For convex lenses, the images can be magnified and located at various positions according to object distance.
Convex lenses are used in a wide range of astronomical equipment, including telescopes and binoculars, to gather more light and magnify distant objects.

Concave Mirrors

Concave mirrors, also known as converging mirrors, are curved inwards.
Just like convex lenses, parallel light rays that hit a concave mirror also converge at a single point, the focus.
Reflecting telescopes primarily use a large concave mirror (primary mirror) to gather light and focus it onto a smaller secondary mirror.
The collected light is then either viewed directly or passed through an eyepiece lens for magnification.
Unlike lenses, mirrors do not suffer from chromatic aberration because they reflect all colours of light equally.
Concave mirrors are favoured in large telescopes as they can be supported from behind, preventing sagging and deformation.

It’s crucial to understand the behaviour of light when it interacts with convex lenses and concave mirrors, as this underpins much of our ability to observe and explore the solar system. All kinds of telescopes, whether they use lenses or mirrors, are examples of these principles in action.