A Travelling Microscope Is Focused On A Mark On A Table. If A Glass Block Of Thickness 18.0cm Is Placed On The Mark By How Many Centimeters Will The Microscope Be Moved Upwards So As To Focus The Mark Once Again? [refractive Index Of Glass = 1.5]

A. 27cm
B. 24cm
C. 9cm
D. 6cm

Correct Answer: Option D

D. 6cm

Explanation

Apparent depth = thickness/refractive index

= 18/1.5 = 12cm

Upward adjustment = 18 – 12

= 6cm

A travelling microscope is focused on a mark on a table. If a glass block of thickness 18.0cm is placed on the mark by how many centimeters will the microscope be moved upwards so as to focus the mark once again? [refractive index of glass = 1.5]