Answer :
In gas-filled detectors like smoke detectors and Geiger tubes, a battery creates voltage that allows the ionization of gas, which in turn generates a current flow. This current is monitored and, if disrupted or altered, can trigger an alarm or provide a count of radiation detected.
In a typical gas-filled detector circuit, such as one found in a smoke detector, a battery creates a voltage between two metal plates. This voltage allows for the ionization of air between the plates, made possible by the presence of a small amount of radioactive americium. The ionization leads to a small, constant current flow. When smoke enters the detector, it disrupts this current. If the current drops below a certain threshold, another circuit will trigger an alarm, indicating the potential presence of a fire.
Similar principles apply to other types of gas-filled detectors, such as the Geiger tube. In the Geiger tube, ionizing radiation creates ion pairs within an insulating gas, and these ions generate a current once a voltage is applied between the tube and a central wire. This current is then counted and used to detect the presence and intensity of ionizing radiation.
