Most optical elements (mirrors, lenses) can be characterized by basically one quantity: their focal length. To understand focal length, we need to know something about the focal point. In the image above, note how the light rays, after they pass through the lens, converge on a single point. Below is a schematic drawing of the above situation. The single point to which the light rays are converging is called the focal point.
Tsk is a sound made by quickly releasing the tongue from the top of the mouth to express disapproval or criticism. An example of tsk is the sound a mother would make while shaking her finger at a child who's done something wrong. (a sound) used to express disapproval, genuine or mock sympathy, etc.: a click, or sucking sound, made by touching the tongue to the hard palate and rapidly withdrawing it.
For XK we have found 11 definitions. What does XK mean? We know 11 definitions for XK abbreviation or acronym in 4 categories. Possible XK meaning as an acronym, abbreviation, shorthand or slang term vary from category to category. Please look for them carefully. XK Stands For: