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.
Incidentally, the bending of a light wave accounts for some of the visual phenomena we often encounter, such as mirages. A mirage is an optical illusion caused when light waves moving from the sky toward the ground are bent by the heated air.