Physics Glossary – G

Galvanometer

An instrument for measuring small currents. When a current is passed through a coil in a magnetic field, the coil experiences a turning force proportional to the current.

Gamma Rays

Are an energetic form of electromagnetic radiation produced by radioactivity or other nuclear or subatomic processes such as electron-position annihilation. Gamma rays are more penetrating than either alpha or beta radiation, but less ionizing. They are a form of electromagnetic radiation. Gamma rays are distinguished from X rays by their origin. Gamma rays are produced by nuclear transitions while X-rays are produced by energy transitions due to accelerating electrons. Because it is possible for some electron transitions to be of higher energy than nuclear transition, there is an overlap between low energy gamma rays and high energy X-rays.

Gay-Lussac Law

Different gases expand in volume by the same amount with the same change in temperature. Named after Joesph Gay-Lussac a French Chemist but better known today as Charles’s Law after fellow countryman Jacque Charles.

Geiger Counter

A device used to detect ionizing radiation like alpha, beta or gamma rays.

Gergorian Telescope

A reflecting telescope with a hole in the primary mirror (parabolic). The light is reflected off the primary mirror and then hits a secondary concave mirror that focused the light down to the viewer. Very similar to a Cassegranian Telescope except that a the secondary mirror that telescope is a convex mirror. Named after James Gergory.

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