A concave lens of focal length 15 cm, forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

23 How are focal length and radius of curvature connected? 24 An object 5 cm high is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagrams and find the position, size and the nature of the image formed. 26 An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image. 27 What is the angle of incidence when the ray reflected back, when it passes from denser to rarer medium.