Draw a ray which passes from the object through the centre of the lens. Some ray diagrams may also show a third ray. Peep holes contain concave lenses. They are set into doors so the occupant can ...

Convex and concave lenses can both be used to correct defects of vision. The most commonly occurring defects of vision are ‘short sightedness’ and ‘long sightedness’. People who are ...

The two types of concave lenses — biconcave and plano-concave — are negative. Meniscus lenses — a third broad type also referred to as convex-concave — can be either positive or negative, depending on ...

Meniscus lenses have one convex and one concave surface with each surface having its own radius or curvature. Applications include lasers and cameras. There are two types of meniscus lenses. Positive ...