1. Calculate the focal lengths for the following thin lenses made of glass of refractive index n = 1.50. The medium surrounding the lens on both sides is air. (a) Converging lens: left surface is convex (looking from the outside of the lens) of radius |r1|=20.0 cm and the right surface is flat. (b) Converging lens: symmetrical double convex lens each surface having radius |r|= 20.0 cm. (c) Diverging lens: symmetrical double concave lens (looking from the outside of the lens) each surface having radius |r| = 20.0 cm. PHYS 2426 Engineering Physics II Problem 34.8 - 1. A slide projector (remember them?) uses a lens of focal length f = 10.0 cm. The slide is placed 10.5 cm to the left of the lens and the image is projected on a screen placed to the right of the lens. (a) What type lens is needed? (b) What is the distance between the screen and the lens? (c) One slide has a picture of the Eiffel Tower that is 3.00 cm high. What is the height of the image projected on the screen?