(a) An object is placed at the centre of curvature (c ) of a concave mirror. Draw the ray diagram to depict the position, size and nature of image formed. (b) Find the focal length of a lens of power - 2.0 D. What type of lens is this ?

(a) An object is placed at the centre of curvature (c ) of a concave m

1.	(a) An object is placed at the centre of curvature (c ) of a concave mirror. Draw the ray diagram to depict the position, size and nature of image formed. (b) Find the focal length of a lens of power - 2.0 D. What type of lens is this ?
Answer» SOLUTION :(a) The ray diagram is The image will be real, inverted and of the same size as that of OBJECT. It will be formed at C. (b) POWER of the LENS = -2.0 D We know power = `1/("FOCAL length in metres")` `therefore` Focal length in metres = `1/("Power")=1/(-2.0)=-0.5m`. Since, the sign of the focal length is -ve, therefore it is a convex lens.