power 4dA convex lens of power + 6D is placed in contact with a concave lens of power – 4D. What is the nature and focal length of the combination. see full answer. Start JEE NEET FoundationOptical power is also referred to as dioptric power, convergence power, refractive power, or refractive power. It is equal to P = 1 f. Dioptre Formula . The Dioptre formula is used to