The diagram shows a cross-section through a human eye. Light from an object is refracted by the cornea and lens to form an image on the retina. The shape of the lens is altered by muscles in the eye to allow images of objects at different distances to be focused on the retina. The closest position at which people can clearly see an object is called the near point. The eye may be modelled as a sphere with a single thin lens as shown. The distance from the centre of the lens to the retina is 2.0 cm. lens . (b) The distance of the near point from the eye increases as people get older. Because of this, older people use reading glasses to enable objects closer than the near point to be seen clearly. A person wants to buyr reading glasses so that the};r can read text clearlyr at a distance of 27.5 cm from their eye. The minimum focal length for this person's eye is 1.93 cm and the distance from the centre of the lens to the retina is 2.0 cm. The available powers of lenses are +1.0 D, +1.5 D, +2.0 D, +2-5 D, +3.0 D and +3.5 D. Show that the appropriate lens needed has a power of +2.0 D. You may ignore the distance between the lens of the glasses and the eve