How Does a One-way Mirror Work? One-way mirrors are designed to
allow a view from one side. CREDIT: InnervisionArt, Shutterstock
How can the good guys see through the mirror while the bad guy
sees nothing but a shiny surface? The mirror used in your
favorite detective show has a thin layer of partially reflective
coating. Only about 80 percent of the light is reflected, while
20 percent passes through. Importantly, the suspect’s room is
about 10 times brighter than the spying detectives’ room, so the
light that passes through the mirror is enough to give the
detectives a good look at the suspect. Because the detectives’
room is not as bright, the scant amount of light that passes
through into the very bright room is not enough to create an
image. MORE FROM LiveScience.com