Question

Which portion of an incoming wavefront is delayed more by a thin prism, and why?

Options

• The ray going through the centre; it travels a shorter path.

• The lower portion; it travels through the greatest thickness of glass.

• Rays near the edge of the lens; they travel through the greatest thickness of glass.

• The central part; it passes through the thickest portion of the lens.

Answer 1

The lower portion travels through the greatest thickness of glass in a thin prism. Because light is slower in glass, this portion is delayed more.