Light can be reflected, transmitted, or absorbed. You have read that EM waves can interact with a material medium in the same ways that mechanical waves do.
The interactions occur when waves pass from one medium to another. Besides bouncing back like an echo, waves may bend or spread out when they strike a new medium. These three ways that waves may interact with matter are called reflection, refraction, and diffraction
PH is the logarithmic measure of the concentration of hydrogen ions in solution. In an aqueous system, the lowest possible concentration of H+ ions (least acidic) is 1x 10^-14. The -log(1x10^-14) = pH of 14
