MR16 Lamps and Bulbs
16 refers to the maximum diameter of the lamp in 1/8 th’s of an inch, so 16 would be 16 x 1/8th which is 2 inches. Other sizes include MR8 (1 inch) and MR11 (1 3/8 inch).
MR16 Lamps operate at 12v and need a transformer to ‘step down’ the mains voltage supply to 12V. The lamps can be dimmed using dimmers designed for low-voltage loads.
The light source for MR lamps is a quartz halogen filament capsule. The reflective coating of MR16 lamps can be either aluminum or dichroic (which is the most common). A dichroic coating is a thin dielectric that allows infrared (heat) radiation from the filament to pass through the reflector to the rear of the lamp while it reflects visible radiation (light) forward . The aluminum coating reflects both infrared and visible radiation in a forward direction.
MR16 bulbs are available as Halogen and low energy LED types with a wide range of light outputs.