Source: Extra Practice
A student measures the thickness of a human hair by looking at it through a microscope of magnification 100. He makes 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5 mm. What is the estimate on the thickness of hair?
Options
Option A is correct
0.035 mm
Option B
3.5 mm
Option C
0.35 mm
Option D
0.0035 mm
Explanation
Magnification = Observed size / Real size. Therefore, Real size = Observed size / Magnification = 3.5 mm / 100 = 0.035 mm. 3.5 mm is the observed size, not the actual size. 0.35 mm and 0.0035 mm result from incorrect division by 10 or 1000 respectively.