Question

An electron micrograph shows a scale bar labeled $2~\mu m$. When measured on the printed image, the scale bar length is 15 mm. What is the magnification of the micrograph?

• A. $2500\times$
• B. $5000\times$
• C. $7500\times$
• D. $15000\times$

Hint:

Always convert units before calculating magnification.

Answer 1

The Correct Option is C

Concept: Magnification is defined as: \[ \text{Magnification} = \frac{\text{Image size}}{\text{Actual size}} \]

Step 1: Convert units.
Given: \[ \text{Actual size} = 2~\mu m = 2 \times 10^{-3}~mm \] \[ \text{Image size} = 15~mm \]

Step 2: Apply formula.
\[ M = \frac{15}{2 \times 10^{-3}} = \frac{15}{0.002} \] \[ M = 7500 \] Final Answer: \[ \boxed{7500\times} \]