An instructor places a fluid substance, with a refractive index of 1.61, between two horizontal panes of flat glass (each of which has n = 1.55). She then illuminates the assembly from above with monochromatic light (? = 700 nm). What is the minimum thickness (in nm) that the liquid layer must have, if the light is to be strongly reflected back toward its source? ??nm

An instructor places a fluid substance, with a refractive index of 1.61, between two horizontal panes of flat glass (each of which has n = 1.55). She then illuminates the assembly from above with monochromatic light (? = 700 nm). What is the minimum thickness (in nm) that the liquid layer must have, if the light is to be strongly reflected back toward its source? ??nm