Scale bar ratio for magnification

Steps:

• Scale bar length on image = 1 cm = 0.01 m.
• Actual length represented = 1 μm = 10^{-6} m.
• Magnification M = image length / actual length = 0.01 / 10^{-6} = 10,000.
• For the electron micrograph print, total M = 20,000×.

Why C is correct:

• The magnification formula M = image size / actual size, with unit conversion, gives ×20,000 for the micrograph.

Why the others are wrong:

• A. ×200 is for light microscope scale bars representing ~50 μm.
• B. ×2000 is for scale bars representing ~5 μm.
• D. ×200,000 is for scale bars representing 0.05 μm.

Final answer: C