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For a compound microscope f₀=1 cm, fₑ=2 cm and the tube length L=20 cm. Then the total magnification is ________.

Asked in GSEB Board August 2020 · Microscopes

Answer: (2) 250

Step-by-step solution

Given: f₀=1 cm, fₑ=2 cm, tube length L=20 cm, and the least distance of distinct vision D=25 cm.

Idea: a compound microscope magnifies twice over — the objective makes a real enlarged image inside the tube, and the eyepiece then views that image as a magnifying glass. The two factors multiply.

Objective: m₀=L/(f₀)=(20)/1=20

Eyepiece, with the final image at the near point: mₑ=D/(fₑ)=(25)/2=12.5

m=m₀× mₑ=20× 12.5=250

Why the other options are wrong

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