What is the formula for the total magnification of a stand magnifier?

What is the formula for the total magnification of a stand magnifier?

• A. MT = (Lateral mag) x (RDM)
• B. MT = (Lateral mag) / (RDM)
• C. MT = (RDM) - (Lateral mag)
• D. MT = Lateral mag + RDM

Answer: (A)

Total magnification for a stand magnifier comes from two independent magnifying effects that combine multiplicatively: the lens’s own lateral magnification and the magnification gained from the viewing distance, called relative distance magnification (RDM). The lens enlarges the image you see directly, while viewing the magnified image at a closer distance increases the angular size it subtends on your retina. Because these two factors act together to determine how large the image appears, they multiply. So the total magnification is the product of the lateral magnification and the relative distance magnification. For example, a lens providing 2x lateral magnification viewed at an RDM of 2x yields a total magnification of 4x. (Adding, subtracting, or dividing these factors would not reflect how these two independent effects combine in practice.)

Total magnification for a stand magnifier comes from two independent magnifying effects that combine multiplicatively: the lens’s own lateral magnification and the magnification gained from the viewing distance, called relative distance magnification (RDM). The lens enlarges the image you see directly, while viewing the magnified image at a closer distance increases the angular size it subtends on your retina. Because these two factors act together to determine how large the image appears, they multiply. So the total magnification is the product of the lateral magnification and the relative distance magnification. For example, a lens providing 2x lateral magnification viewed at an RDM of 2x yields a total magnification of 4x. (Adding, subtracting, or dividing these factors would not reflect how these two independent effects combine in practice.)