A travelling microscope is focused on a mark on a table. If a glass block...

PHYSICS
WAEC 2006

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 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: D. 6cm

Explanation

Apparent depth = \(\frac{\text{thickness}}{\text{refractive index}}\)

= \(\frac{18}{1.5} = 12cm\)

Upward adjustment = 18 - 12

= 6cm



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