A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again ?

Question

Dr. Abubacker · Accepted Answer

[Solution from source] A slab of thickness t and refractive index μ makes the mark appear raised by t(1 − 1/μ) = 3(1 − 1/1.5) = 1 cm. Since the image of the mark is now 1 cm higher, the microscope must be raised by 1 cm. Moving it down would take it further out of focus. Answer (1).

Q. A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again ?

Explanation

Reviewed by Dr. Abubacker

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