10 exam-style questions with answers and explanations. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The CHP exam has 150 questions and runs 3 hours.
These 10 free CHP questions are organized by exam domain, so you can see how each part of the Certified Health Physicist blueprint is tested. Reveal the answer and explanation under each question.
A wipe (smear) test is performed over a 100 cm² surface. The wipe is counted at 900 net counts per minute (cpm) on a detector whose efficiency for the nuclide present is 15%. What is the removable surface contamination?
Correct answer: C - 6,000 dpm/100 cm²
An instrument must separate alpha particles from beta particles in a mixed field by comparing pulse heights. In which region of the gas-filled detector operating curve must it operate?
Correct answer: B - Proportional region
In low-level counting, which quantity is the threshold used to decide whether a measured sample contains activity above background, controlling the rate of false-positive (Type I) decisions?
Correct answer: A - The critical level (L_C)
A GM survey meter reads progressively lower than the true value as it is moved into an increasingly intense radiation field. This underresponse at high count rates is BEST explained by:
Correct answer: D - Dead-time (resolving-time) count losses at high count rates
An air sample is collected by drawing air through a filter at 2 liters per minute for 100 minutes. After collection and decay corrections, the filter contains 4,000 dpm of a long-lived radionuclide. What was the average airborne concentration during sampling?
Correct answer: B - 20 dpm/L
Under U.S. NRC regulations (10 CFR Part 20), what is the annual occupational dose limit for the total effective dose equivalent (TEDE) to an adult radiation worker?
Correct answer: B - 5 rem (0.05 Sv)
In one year a worker accrues a deep-dose equivalent of 1.8 rem from external exposure and a committed effective dose equivalent of 2.5 rem from an intake of radioactive material. What is the worker's TEDE for the year?
Correct answer: D - 4.3 rem
Which of the following is a legally enforceable requirement, rather than a recommendation or a voluntary consensus standard?
Correct answer: D - A regulation codified in Title 10 of the CFR
Under 10 CFR Part 20, an area in which an individual could receive a dose equivalent greater than 5 mrem (0.05 mSv) in one hour at 30 cm from a radiation source must, at minimum, be posted as a:
Correct answer: A - Radiation Area
A gamma source produces an exposure rate of 800 mR/hr at a work location. Using a shield whose half-value layer (HVL) is 1.2 cm at this photon energy, what shield thickness reduces the exposure rate to 100 mR/hr (assume good geometry)?
Correct answer: C - 3.6 cm
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