Professor Johnson’s glasses have a front radius of +0.12m and a back radius of -0.08m. What is the focal length of his glasses if the index of refraction of the glass is 1.5? What is their strength in dioptres? Given that he sees things in the normal range by his glasses (near point = 25 cm; far point = infinity), what is his near and far points without this glasses? (His glasses are one cm in front of his eye’s lens and his retina is 1.7 cm behind his lens.)