A tachometer is an instrument designed to measure the rotation speed of a shaft or disk. Tachometers generally measure rotations per minute (RPM) though some models also serve as rate meters and/or totalizers.
What device measures its the proper acceleration relative to freefall, and is increasingly used in portable electronic devices and video game controllers to detect the orientation of the device or provide game input?
What device, a tool for studying astronomical phenomena, uses the fact that when a material is heated to incandescence it emits light that is characteristic of the atomic makeup of the material?
What is the name for a net of fine lines or fibres in the eyepiece of a sighting device, such as a telescope, a telescopic sight, a microscope, or the screen of an oscilloscope?