Define the principal focus of a convex lens and that of a concave lens.

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Solution

The principal focus of a lens is defined as the point through which a parallel light after refraction passes through in the case of a convex lens and appears to pass through in the case of a concave lens

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Similar questions

(a) Explain with the help of a diagram, why the concave lens is also called a diverging lens. (b) Define the principal focus of a concave lens.

(a) With the help of a labelled diagram explain how a convex lens converges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the convex lens on the diagram.
(b) State whether the convex lens has a real focus or a virtual focus. (c) List some things that convex lens and concave mirror have in common.

(a) With the help of a labelled diagram, explain how a concave lens diverges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the concave lens on the diagram. (b) State whether concave lens has a real focus or a virtual focus. (c) List some things that concave lens and convex mirror have in common.

What is the difference between focus and principal focus of concave and convex lenses

Q. Define principal focus of a convex lens. Draw light ray diagram of an image formed, when the object is placed in between principal focus

F

and

2 F

.
Write lens formula.
Calculate power of a lens if its focal length is

0.5 m

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