What is the image magnification factor if the focus to film distance is 140 cm and the focus to skin distance is 100 cm?

The image magnification factor in radiography is calculated by comparing the distances from the focus (or source) to the film and from the focus to the skin (or object). The formula for magnification is defined as the ratio of the focus-to-film distance to the focus-to-skin distance.

In this case, the focus to film distance is 140 cm, and the focus to skin distance is 100 cm. By applying the magnification factor formula, we divide the focus to film distance (140 cm) by the focus to skin distance (100 cm):

[

\text{Magnification Factor} = \frac{\text{Focus to Film Distance}}{\text{Focus to Skin Distance}} = \frac{140 \text{ cm}}{100 \text{ cm}} = 1.4.

]

This indicates that the image is magnified by a factor of 1.4, which reflects that the image appears larger than the actual size of the object due to the distance from the source to the film being greater than from the source to the object.

Thus, the magnification factor of 140/100 is indeed correct as it represents the relationship between the two distances accurately.