Let's tackle subtraction first. Subtraction in hexadecimal works similar to subtraction in decimal. Let's do a pair of decimal problems and see if we can parallel the solution method in hex. Suppose we want to subtract 1586 - 243 (in decimal).
Refraction of Light Rays. the bending or deflection of light rays as they pass through the various media of the eye that include the conjuctiva, cornea, aqueous humor, lens, and vitreous body.
When this happens, light changes speed and the light ray bends, either toward or away from what we call the normal line, an imaginary straight line that runs perpendicular to the surface of the object. The amount of bending, or angle of refraction, of the light wave depends on how much the material slows down the light.