29. According to the inverse square law, the intensity of radiation is __ proportional to the __ from the source of radiation. a. Directly; distance b. Directly; square of the distance c. Inversely; distance d. Inversely; square of the distance A B C D 30. Aluminum filters: a. Remove more penetrating x-rays from the beam b. Decrease the mean penetrating ability of the x-ray beam c. Remove high-energy x-rays from the beam d. Reduce the intensity of the x-ray beam A B C D

29. **D**. According to the inverse square law, the intensity of radiation is **inversely** proportional to the **square of the distance** from the source of radiation. This means that if you double the distance, the intensity decreases to one-fourth its original value.<br /><br />30. **D**. Aluminum filters primarily **reduce the intensity of the x-ray beam**. They do this by absorbing some of the lower-energy x-rays. While they do remove *some* lower-energy x-rays, their primary effect is an overall reduction in beam intensity. Options A and C imply removing *higher* energy x-rays, which is incorrect. Option B is also incorrect; by removing lower-energy x-rays, the *mean* penetrating ability would actually slightly *increase*, although this effect is less significant than the overall reduction in intensity.<br />