Question 7 a. The radius of curvature of a plano-convex lens ismeasured to be 2 metres, and the focal length in air (n = 1) ismeasured to be 4 metres. i. What is the power of the lens? [2marks] ii. What is the refractive index of the lens material? [4marks] b. A toy Dalek is placed 40 cm in front of a converging lensof focal length f1 = 20 cm; another converging lens 60 cm behindthe first has a focal length of f2 = 10 cm. i. Draw a ray tracediagram for this optical system [4 marks] ii. Show where the imageproduced by the first lens appears on your diagram. Is it a real orvirtual image? [3 marks] iii. What is the magnification of theobject at the first image? [1 marks] iv. Show where the final imageappears on your diagram. Is it a real or virtual image? [3 marks]v. What is the magnification of the first image at the final image?[1 mark] vi. What is the magnification of the object at the finalimage? [2 marks]
