Consider the element sodium. it's atomic number is and equals a) 11; the number of protons b) 12; the number of neutrons c) 23; the sum of protons and neutrons d) 23; the number of electrons

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.