Magnification is caused by:

• A. Short SID
• B. Long SID
• C. Short OID
• D. Long OID

Answer: (A)

Magnification comes from the geometry of the X-ray setup—the image you see is larger than the object when the rays spread out more between the source, the object, and the receptor. The magnification factor is tied to the distances: shorter Source-to-Image Distance (SID) increases magnification because the X-ray beam diverges more as it travels a shorter path, causing the projected image on the receptor to appear larger. The math idea is that magnification depends on SID and the distance from the source to the object (SOD), with SOD itself equal to SID minus the Object-to-Image Distance (OID). If OID stays constant and SID is shortened, the geometry makes the image bigger on the receptor, so magnification goes up. Long SID would do the opposite and reduce magnification. While increasing OID also increases magnification, among these options the clearest way to produce magnification is using a short SID.