A convex lens is said to have a real focus and a concave lens a Virtual Focus.Why?
Convex lenses bend parallel light rays to form a point at a given distance, called the focal length.
Concave Lenses bend parallel light rays in the opposite Direction, so they never form a point. By extrapolating the lines, you can calculate a virtual focal point in the opposite direction.
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- (a) Explain with the help of a diagram, why the concave lens is also called a perging lens.(b) Define the principal focus of a concave lens.
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