A concave lens is placed in the path of convergent rays. The rays are focussed on the axis 15 cm behind the lens. Where would these rays have been focussed in the absence of the lens ? Focal length of the lens is 30 cm.

A concave lens produces an image 20 cm from the lens of an object placed 30 cm from the lens. The focal length of the lens is:

A beam of light converges at a point P. Nnw a lens is placed in the path of the convergent beam 12cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20 cm, and (b) a concave lens of focal length 16 cm ?

A beam of light converges to a point P , A lens is placed in the path of the convergent beams 12 cm from P. At what point does the beam converge if the lens is a. A convex lens of focal length 20 cm. b. A concave lens of focal length 16 cm ?

A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12 cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20 cm, and (b) a concave lens of focal length 16 cm ?

A beam of light converges to a point P. A lens is placed in the path of the convergent beam 12 cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20 cm. (b) a concave lens of focal length 16 cm.