Give two reasons why in practice a convex lens may not bring parallel rays to an exact point focus?

Question: this is a question from the book of Explaining Physics GCSE edition by Stephen Pople.

Answer: This is caused by aberrations. Two examples of aberrations are chromatic aberration and spherical aberration. Chromatic aberration refers to different wavelengths getting focused differently because the index of refraction depends on wavelength. Spherical aberration refers to the curvature actually not being ideal for focusing rays to one point.

Related Questions

Related Items