1. 25.4
Radiation in Your Life
In a smoke detector, radiation from the Americum nuclei ionizes the nitrogen and oxygen in smoke-free air, allowing a current to flow. When smoke particles get in the way, a drop in current is detected by an electronic circuit, causing it to sound an alarm. You will learn about some of the other practical uses of radiation.

2. Detecting Radiation What are three devices used to detect radiation?
25.4
Detecting Radiation
Detecting Radiation
What are three devices used to detect radiation?

3. 25.4
Detecting Radiation
Ionizing radiation is radiation with enough energy to knock electrons off some atoms of the bombarded substance to produce ions.
Devices such as Geiger counters, scintillation counters, and film badges are commonly used to detect radiation.

4. 25.4
Detecting Radiation
Radiation can produce ions, which can then be detected, or it can expose a photographic plate and produce images.
Radiation can expose a photographic plate.

5. A Geiger counter uses a gas-filled metal tube to detect radiation.
25.4
Detecting Radiation
Geiger Counter
A Geiger counter uses a gas-filled metal tube to detect radiation.

6. Scintillation Counter
25.4
Detecting Radiation
Scintillation Counter
A scintillation counter uses a phosphor-coated surface to detect radiation.

7. 25.4
Detecting Radiation
Film Badge
A film badge consists of several layers of photographic film covered with black lightproof paper, all encased in a plastic or metal holder.

8. Using Radiation How are radioisotopes used in medicine? 25.4

9. 25.4
Using Radiation
Neutron activation analysis is a procedure used to detect trace amounts of elements in samples.
Neutron activation analysis is used by museums to detect art forgeries, and by crime laboratories to analyze gunpowder residues.

10. 25.4
Using Radiation
Radioisotopes can be used to diagnose medical problems and, in some cases, to treat diseases.

11. 25.4
Using Radiation
This scanned image of a thyroid gland shows where radioactive iodine-131 has been absorbed.
This scanned image of a thyroid gland shows where radioactive iodine-131 has been absorbed. Doctors use these images to identify thyroid disorders.

12. 25.4 Section Quiz.
1. Ionizing radiation can remove _______ from atoms.
protons
neutrons
positrons
electrons.

13. 25.4 Section Quiz.
2. Which of the following is NOT a device used to detect radiation?
geiger counter
scintillation counter
film badge
radioisotope

14. 25.4 Section Quiz.
3. Choose the correct words for the space. When a tumor is treated by radiation, more cancer cells than normal cells are killed because cancer cells ____________ than normal cells.
are more susceptible to damage because they grow faster
absorb more radiation because they are larger
grow slower
are smaller

15. 25.4 Section Quiz.
4. How do scientists detect thyroid problems?
with teletherapy
by neutron activation analysis
using an iodine-131 tracer
using a radioisotope sealed in a gold tube