The law that governs the effect of SID on receptor exposure is:

The law that governs the effect of SID on receptor exposure is:

• A. inverse square law
• B. direct square law
• C. law of Thibodeau and Bergonia
• D. Ohm's law

Answer: (A)

The main concept here is how the distance from the X-ray source affects the amount of exposure reaching the receptor. This is governed by the inverse square law, which says that the intensity of radiation is inversely proportional to the square of the distance from the source. So, if you double the source-to-image distance, receptor exposure falls to one quarter; if you halve the distance, exposure increases by a factor of four. This happens because the X-ray beam fans out as it travels, spreading photons over a larger area as distance increases. This is distinct from the other options. A direct square law would imply exposure increases with distance, which is opposite of what actually happens. Ohm's law deals with electrical circuits, not X-ray exposure. The law named for two individuals here isn't a real law governing radiography.

The main concept here is how the distance from the X-ray source affects the amount of exposure reaching the receptor. This is governed by the inverse square law, which says that the intensity of radiation is inversely proportional to the square of the distance from the source. So, if you double the source-to-image distance, receptor exposure falls to one quarter; if you halve the distance, exposure increases by a factor of four. This happens because the X-ray beam fans out as it travels, spreading photons over a larger area as distance increases.

This is distinct from the other options. A direct square law would imply exposure increases with distance, which is opposite of what actually happens. Ohm's law deals with electrical circuits, not X-ray exposure. The law named for two individuals here isn't a real law governing radiography.