Integer (computer science) In computer science, an integer is a datum of integral data type, a data type that represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values. Integers are commonly represented in a computer as a group of binary digits (bits).
critical angle. Definition: The angle or greater, measured at the interface between a denser medium and a less dense in the same plane as the incident light, at which total internal reflection takes place - i.e. light is reflected back into the medium.
When one is exactly at the critical angle, the light behaves in a way that may be interpreted as something in between refraction and reflection: it continues in a direction that is tangent to the boundary of the mediums. When the angle is smaller than the critical angle, we get refraction. At the critical angle, $\theta_2$ of the refraction becomes 90 degrees, so we get the tangent propagation. At angles larger than the critical ones, there is a discontinuity: the equation for $\theta_2$ (arcsine of something) has no solutions which is why we get a total internal reflection.