An angular magnification of 30X is desired using an eye piece of focal length 5cm and an objective lens. Find the magnifying power of objective lens. [Given angular magnification is achieved in case of normal adjustment]
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Solution
Given:
m=30 and fe=5cm
We know magnifying power of eyepiece, me=Dfe
⇒me=255=5
Now, we know that total magnification,
m=me×m0
⇒30=5×m0
∴m0=6
Hence, (A) is the correct answer.
Key Concept: Total magnification of a combination of lenses is equal to the product of magnification of individual lenses.