The wire that carries the current from the power source to the outlet or receptacle is the hot wire. Whenever you see a black wire, you know it is hot. There are other wires that carry current in more complicated circuits, but black are always hot.
The minimum angle at which total internal reflection occurs is known as the critical angle (for Perspex this is about 43Ë). At any angle greater than the critical angle, total internal reflection occurs and the light ray obeys the normal rules for reflection (i.e. angle of incidence = angle of reflection). 1  Page. 2  1. 3  2.
This light is then reflected back into space at another angle, known as the angle of reflection. As shown above, the angle of incidence for visible light is equal to the angle of reflection. This concept, which holds true for all types of electromagnetic radiation, is often termed the law of reflection.