Detection of Radioactivity Quiz
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5 questions, one answer each
Each answer is checked as you go, with why.
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1. What is meant by background radiation?
- A. Low-level ionising radiation that is present all around us from natural and man-made sources
- B. Radiation that only comes from radioactive elements in the Earth's crust
- C. The maximum radiation level that a person can safely be exposed to
- D. Radiation produced only by cosmic rays from outer space
2. Which of the following is NOT a significant source of background radiation?
- A. Radon gas from rocks and soil
- B. Cosmic rays from space
- C. Food and drink containing radioactive isotopes
- D. Ultraviolet radiation from the Sun
3. A student measures the count rate from a radioactive source placed near a detector. The detector reads 240 counts/minute. The background radiation count rate is measured separately as 30 counts/minute. What is the corrected count rate from the source?
- A. 30 counts/minute
- B. 210 counts/minute
- C. 240 counts/minute
- D. 270 counts/minute
4. In a laboratory, a radiation detector is set up to measure count rate in counts/s. Over 10 seconds, the detector records 450 counts with a radioactive source present, and 50 counts without the source over the same time period. What is the corrected count rate from the source in counts/s?
- A. 5 counts/s
- B. 40 counts/s
- C. 45 counts/s
- D. 50 counts/s
5. Why is it essential to measure background radiation separately when determining the activity of a radioactive source?
- A. To ensure the detector is functioning correctly and has sufficient battery
- B. To identify which sources of background radiation are present in the environment
- C. To subtract the constant background count rate from measurements so that only the radiation from the source is accounted for
- D. To ensure that cosmic rays do not interfere with the measurement of radon gas