Sunlight is focused on a sheet of paper using a symmetric biconvex lens. The paper burns in the shortest time when the lens is held 30 cm above it, so the focal length is 30 cm. The magnitude of the radius of curvature of each lens surface is 60 cm. If the refractive index of the lens material is α ÷ 10, find α.
Physics · Geometrical optics · lens and combination lens,silvered lens
Sunlight is focused on a sheet of paper using a symmetric biconvex lens. The paper burns in the shortest time when the lens is held 30 cm above it, so the focal length is 30 cm. The magnitude of the radius of curvature of each lens surface is 60 cm. If the refractive index of the lens material is α ÷ 10, find α.