For a thin prism of small angle A, deviation = (n-1)A. For two thin prisms of same glass material but different apex angles in contact with reversed orientation producing zero deviation. For white light dispersion:

Answer: Non-zero (chromatic effect remains).

• A Also zero in typical laboratory settings
• B Non-zero (chromatic effect remains)
• C Equal to deviation of each under usual circumstances
• D Depends on glass type according to most researchers

Concave mirror ray construction: a ray parallel to the axis reflects through F, and a ray through F reflects parallel, locating the inverted real image. Image: Maxmath12, CC0, via Wikimedia Commons.