Question

The "switchable" privacy glass system description that follows is missing a key element. What must be added to make this system work? Two layers of polyester film coated with transparent conductive material and a layer containing liquid crystal sandwiched in between. The film is positioned between two layers of glass.

Answer

Electrical current is required to make the system work. With current, the molecules in the crystals line up and allow light to pass (transparent glass). Switched off, the crystals return to their unaligned state, diffusing the transmission of light (translucent glass).