Worksheet: Refracted Images

In this worksheet, we will practice calculating the focal and magnification properties of an optical system consisting of convex refracting lenses.


A convex surface made of Plexiglas has a radius of curvature of 80 cm. An object is located at a point 30 cm from the vertex of the Plexiglas surface, along its optical axis. Both object and surface are immersed in water. The refraction of light through the convex surface forms an image. Use a value of 1.65 for the refractive index of Plexiglas and a value of 1.33 for the refractive index of water to calculate the properties of the image formed.

How far from the object does the image by refraction form?

What magnification does the object produce?

  • A+2.2
  • B+2.0
  • C+1.0
  • D+1.4
  • E+1.7


A convex surface made of glass has a curvature of radius 80.0 cm and a refractive index of 1.5. An object is held 30.0 cm away from the vertex of the convex surface, along the surface’s optical axis.

What is the distance between the object and the image formed by refraction?

What magnification does the surface produce?

  • A+2.0
  • B+2.2
  • C+1.5
  • D+1.3
  • E+1.8

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