Admin Table of Contents
How do smoke detectors work BBC Bitesize?
Smoke alarms A household smoke alarm measures the movement of alpha particles across a small gap. If smoke enters the detector, it will absorb the alphas and the detector will measure a drop in the number getting across the gap. This drop in measurement will trigger the alarm to sound.
What type of radiation do smoke detectors emit?
Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged.
How would you describe a smoke detector?
A smoke detector is a sensor that detects smoke as a primary indication of fire. It provides a signal to a fire alarm system in a large building, or produces an audible and visual signal locally in a room or a home.
What does the radioisotope in a smoke detector normally do?
The Am-241 emits alpha particles which ionise the air and allow a current between two electrodes. If smoke enters the detector it absorbs the alpha particles and interrupts the current, setting off the alarm.
How does a smoke detector work GCSE physics?
An isotope of americium which emits alpha particles is used in smoke alarms. Alpha radiation ionises the air and this allows a small current to flow between two electrodes. Alpha is weakly penetrating so smoke stops it, the current drops and the alarm goes off.
What is the radiation emitted from radioactive materials that is a high energy electromagnetic wave?
Gamma rays are similar to visible light, but have much higher energy. Gamma rays are often emitted along with alpha or beta particles during radioactive decay.
How do carbon monoxide detectors work?
Carbon monoxide detectors sound an alarm when they sense a certain amount of carbon monoxide over time. Electrochemical sensor: electrodes in a chemical solution sense changes in electrical currents when they come into contact with carbon monoxide, and this change triggers the alarm.
Are smoke alarms safe radiation?
Whilst perfectly safe to residents, ionisation fire alarms are banned in several countries as they contain small quantities of radioactive material (Americium 241) meaning there are storage and disposal issues.
Why is smoke detector used?
A smoke detector is an electronic fire-protection device that automatically senses the presence of smoke, as a key indication of fire, and sounds a warning to building occupants. Commercial and industrial smoke detectors issue a signal to a fire alarm control panel as part of a building’s central fire alarm system.
What do we use radioisotopes for?
Radioisotopes are used to follow the paths of biochemical reactions or to determine how a substance is distributed within an organism. Radioactive tracers are also used in many medical applications, including both diagnosis and treatment.
How is a radioactive material different from a material that is not radioactive?
How is a radioactive material different from a material that is not radioactive? Radioactive materials: -emit invisible radiation. -change into different materials.
How dangerous is the radioactive material in smoke detectors?
The amount of radioactive material contained in ionization smoke detectors is so small it does not pose a risk to human health . However, some municipalities prohibit the disposal of ionization detectors in the municipal waste stream. First Alert offers a complimentary disposal service for up to 4 intact First Alert, Onelink, or BRK detectors.
What radioactive element is found inside a smoke detector?
Smoke detectors contain the radioisotope Americium 241 (AM-241) or Radium 226 (RA-226) which is a radioactive element (also known as a source) inside the smoke detector used to make the smoke detector function. It is said by the National Fire Protection Association (NFPA) that all smoke detectors be replaced every 10 years for full accuracy.
Why is americium-241 used in smoke detectors?
Americium is used in the most common type of household smoke detector, which uses 241 Am in the form of americium dioxide as its source of ionizing radiation . This isotope is preferred over 226 Ra because it emits 5 times more alpha particles and relatively little harmful gamma radiation.
How is radioactivity used in smoke detectors?
Ionization-type smoke alarms have a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.