Work Step by Step
a. The focal length of a lens depends on the fluid in its environment. The lensmaker’s equation contains a factor of (n – 1), where n is the index of refraction of air. If the same lens is immersed in some other fluid with a different index of refraction, the calculated focal length changes. b. The focal length of a spherical mirror is independent of the surrounding fluid. Image formation for mirrors is determined by reflection of the light rays, and does not depend on the index of refraction of the fluid in which the mirror is immersed.