7. A pen shaped device which can sense light, and is used to point at spots on a video screen. A.Mouse B.Light pen C.Joystick D.Plotter E.None of the above
Option B Solution: Light Pen : A light pen is a light-sensitive computer input device, basically a stylus, that is used to select text, draw pictures and interact with user interface elements on a computer screen or monitor. The light pen works well with CRT monitors because of the way such monitors scan the screen, which is one pixel at a time, giving the computer a way to keep track of the expected scanning time by the electron beam and infer the pen's position based on the latest timestamp of the scanning.
