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Physics
Half-Life + Uses/Risks of Nuclear Radiation (Section 7)
| Question | Answer |
|---|---|
| What is a half-life? | The time taken for half of the radioactive atoms currently present to decay |
| What does a short half-life mean? | Activity falls quickly, due to lost of nuclei decaying quickly |
| What does a long half-life mean? | Activity falls slowly, as nuclei take a long time to decay |
| What is radioactivity measured in? | Becquerels (Bq) |
| What does becquerel mean? | 1 decay per second |
| Name 4 uses of nuclear radiation | 1. Treat cancer 2. Sterilise food 3. Sterilise medical equipment 4. Smoke detectors |
| How is nuclear radiation used in medical tracers? | - Source of radiation is swallowed - It can then be detected externally from inside the body - Doctors can see if organs are working properly |
| What kind of radiation must be used for medical tracers and why? | Gamma or beta, as they can penetrate body tissues and aren't strongly ionising |
| What is required of the radioactive source used for medical tracers? | A short half-life, as radioactivity needs to disappear quickly inside patient |
| What kind of radiation is used to treat cancer? | Gamma rays |
| What kind of radiation is used to sterilise food and medical equipment? | Gamma rays |
| Why is radiation a better method of sterilisation of food and medical equipment than boiling? | It doesn't involve high temperature that may damage the food/equipment |
| When sterilising food and medical equipment, why does the radioactive source have to have a long half-life? | So it doesn't need replacing too often |
| What kind of radiation is used to detect leaks in pipes? | Gamma rays |
| How does radiation help detect leaks in pipes underground? | The source is fed into the pipe and people know there is a leak if more radiation is recorded in one area compared to the rest of the pipe |
| Why are beta and gamma particles more dangerous when outside the body? | If they get inside, most radiation will pass out without doing damage |
| Why is alpha radiation only dangerous inside the body? | It can't penetrate skin |
| Why is radiation bad for cells in the body? | Radiation collides with molecules in the cells, ionising them, which damages or destroys the molecule |
| What does radiation cause in cells which leads to cancer? | Mutations, which then divide uncontrollably |
| What is the effect of high doses of radiation? | Cells are killed completely, causing radiation sickness (not cancer) |
| What is the effect of low doses of radiation? | Minor damage is caused without killing the cell, which leads to mutations |
| What word is used to describe exposure to radiation? | Irradiation |
| Does irradiation make something radioactive? | No, it is simply the exposure to a radioactive source |
| Name 2 ways you could reduce the risk of irradiation? | 1. Keeping sources in lead-lined boxes 2. Standing behind barriers/being in different room |
| What is an object called if unwanted radioactive atoms get onto it? | Contaminated |
| Name 2 ways to avoid contamination when handling radioactive sources | 1. Use gloves/tongs 2. Wear a mask |
| How is high-level radioactive waste disposed of? | Put in a glass container, which is sealed in a metal canister and buried deep underground |
| Why must an area where high-level radioactive waste is buried must not suffer from earthquakes? | Earth quakes could move rocks, which disturb the canisters and allow waste to leak out |
Created by:
JoeMather
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