Question

What is concave lens ?? ​

Answer 1

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The principal focus of a concave lens is a point on its principal axis from which light rays, originally parallel to the axis appear to diverge after passing through the concave lens. Concave lens has virtual focus. 

Answer 2

Q.What is concave lens ??

✍A concave lens is a glass lens which diverges light rays and has 2 principal focii and radius of curvature.