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?

1 cm upward

4.5 cm downward

1 cm downward

2 cm upward

Solution

1 cm upward

Apparent depth of mark as seen through a glass slab of thickness x and refractive index $straight mu$ is
$Apparent space depth space equals space fraction numerator Real space depth over denominator Refractive space index end fraction or space space space space straight x apostrophe space equals space straight x over straight mu space equals space fraction numerator 3 over denominator 1.5 end fraction space equals space 2 space cm$
As image appears to be raised by 1 cm, therefore, microscope must be moved upward by 1 cm.

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Wave Optics

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?

1 cm upward

4.5 cm downward

1 cm downward

2 cm upward

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For Daily Free Study Material Join wiredfaculty

Wave Optics

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? 1 cm upward 4.5 cm downward 1 cm downward 2 cm upward

Some More Questions From Wave Optics Chapter

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

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?

1 cm upward

4.5 cm downward

1 cm downward

2 cm upward