A student measures the thickness of a human hair by looking at it through a microscope of magnificat

Question

A student measures the thickness of a human hair by looking at it through a microscope of magnification 100. He finds that the average width of the hair in the field of view is $3.5	ext{ mm}$. What is the estimate on the thickness of the hair?

Professor PC Thomas Classes · Answer

Magnification $m = \frac{	ext{Image size}}{	ext{Object size}}$. Hence, Object size $= \frac{	ext{Image size}}{m} = \frac{3.5	ext{ mm}}{100} = 0.035	ext{ mm}$.