RADIOACTIVITY
Uses of Radioactivity
1. Used as smoke detectors in domestic kitchens and public buildings like offices
and hotels
The source used is Americium – 241 a radioactive source of Alpha radiation
- Alpha radiation from the source falls on the detector causing a small current to
flow in the detector. The output from the detector is off so the alarm will be
silent.
- When the smoke enters the gap between the source and the detector, it
absorbs the Alpha radiation and no current flows in the detector so the
processing circuit switches on causing the alarm to sound
- Alpha radiations are used because Alpha is easily absorbed by the smoke
2. They are used to measure Thickness of paper
This ensures that the papers are of uniform thickness. Also in Aluminum
sheeting, Beta radiation is used to ensure uniform sizes of the aluminium sheets
3. They are used in fault detection
This is to detect the faults in manufactured goods like pipes whereby the
photographic film is stripped around the pipe and the radioactive substance
placed inside the pipe and then the film produced is studied
, 4. They are used to trace the underground flow of water
5. They are used in carbon dating to trace the age of archaeological objects
All living things contain carbon. Plants get carbon from the atmosphere as carbon
dioxide and as animals eat the plants, they also get the carbon, then the
predators that feed on these animals also get the carbon from the animals’ meat.
When a living organism dies, the carbon – 14 in its body decays so the amount of
carbon – 14 remaining in its body decreases. We can measure the amount
remaining then workout when the organism was alive
Examples:
1. Carbon has two isotopes of carbon – 12 and carbon – 14. Carbon – 14 is
Radioactive
The proportion of the two isotopes in living things remains constant while they are
Alive But when they die, the proportion of Carbon – 14 drops as the isotope
decays
Archaeologists studying a bone find it emits 20 counts/s, whereas similar
Modern bone emits 80 counts/s.
The half-life of carbon-14 is 5700 years. Use this information to estimate the age
Of the bone that the archaeologists found
Time (years) Counts/s
t=0 80
t = 5700 40
t = 11400 20
The bone is about 11400 years old
Uses of Radioactivity
1. Used as smoke detectors in domestic kitchens and public buildings like offices
and hotels
The source used is Americium – 241 a radioactive source of Alpha radiation
- Alpha radiation from the source falls on the detector causing a small current to
flow in the detector. The output from the detector is off so the alarm will be
silent.
- When the smoke enters the gap between the source and the detector, it
absorbs the Alpha radiation and no current flows in the detector so the
processing circuit switches on causing the alarm to sound
- Alpha radiations are used because Alpha is easily absorbed by the smoke
2. They are used to measure Thickness of paper
This ensures that the papers are of uniform thickness. Also in Aluminum
sheeting, Beta radiation is used to ensure uniform sizes of the aluminium sheets
3. They are used in fault detection
This is to detect the faults in manufactured goods like pipes whereby the
photographic film is stripped around the pipe and the radioactive substance
placed inside the pipe and then the film produced is studied
, 4. They are used to trace the underground flow of water
5. They are used in carbon dating to trace the age of archaeological objects
All living things contain carbon. Plants get carbon from the atmosphere as carbon
dioxide and as animals eat the plants, they also get the carbon, then the
predators that feed on these animals also get the carbon from the animals’ meat.
When a living organism dies, the carbon – 14 in its body decays so the amount of
carbon – 14 remaining in its body decreases. We can measure the amount
remaining then workout when the organism was alive
Examples:
1. Carbon has two isotopes of carbon – 12 and carbon – 14. Carbon – 14 is
Radioactive
The proportion of the two isotopes in living things remains constant while they are
Alive But when they die, the proportion of Carbon – 14 drops as the isotope
decays
Archaeologists studying a bone find it emits 20 counts/s, whereas similar
Modern bone emits 80 counts/s.
The half-life of carbon-14 is 5700 years. Use this information to estimate the age
Of the bone that the archaeologists found
Time (years) Counts/s
t=0 80
t = 5700 40
t = 11400 20
The bone is about 11400 years old
