What is a Geiger counter?

Geiger counters detect and measure radioactivity.
H. Geiger and E.W. Muller invented the Geiger counter in 1928.

With a Geiger counter you can check materials and environment for radioactivity.

Radioactivity is the spontaneous emission of energy from certain elements, most notably uranium. There are three forms of energy associated with radioactivity; alpha, beta and gamma radiation. The classifications were originally made according to the penetrating power of the radiation.

Alpha rays were found to be nuclei of helium atoms, two protons and two neutrons bound together. Alpha rays have weak penetrating ability; a couple of inches of air or a few sheets of paper can effectively block them.

Beta rays were found to be electrons, identical to the electrons found in atoms. Beta rays have a greater penetrating power than Apha rays and can penetrate 3mm of aluminum.

Gamma rays are high energy photons. This has the greatest penetrating power, being able to pass through several centimeters of lead and still be detected on the other side.


EDIT
Quote: "Bob Blaylock: Some good information, but doesn't answer the question"

A Geiger counter is a device used to detect and measure radioactivity.
Does that answer the question?

  A geiger counter is a device that detects ionizing radiation.

  At its heart is a Geiger-Mueller tube, which contains gas which is arranged around a high-voltage electrode in such a manner as to be just barely on the verge of ionizing.  When a particle or wave of ionizing radiation strikes one of the gas molecules, in the G-M tube, this triggers an avalanche effect that causes all the gas to momentarily ionize and to conduct electrical current.  This produces the “click” that you hear when a geiger counter is operating.  The more radiation there is, the more often this will occur, and the more rapidly it will click.

  Having been told that a geiger counter would probably not respond to x-rays, I've made a point of bringing mine along on those few occasions that I've had to be x-rayed.  I can tell you, therefore, from direct experience, that my geiger counter does indeed respond to x-rays.

A gieger counter is an electronic instrument that responds to some

types of radiation.


The Gieger- Muller tube is the basis for the instrument.

An inert gas is effected (Ionized) by the passage of certain particles.


The ionization causes small current paths across the tube. These

currents are amplified and produce a reading on a meter or the

famous click.


Their are other types of sensors today (solid-state).


hope this helps