Editing Halogen lamp (section)

==Form factors==
{{see also|Incandescent light bulb#Bulb shapes}}
Halogen lamps are available in a series of different shapes and sizes, and are designated according to a coding system that specifies the diameter of the bulb as well as whether or not the bulb has a built-in infrared-transparent [[dichroic]] reflector. Many such lamps have designations that begin with the letter "T" to indicate that they are "tubular" followed by a number indicating the diameter of the tube in eighths of an inch: a T3 bulb, then is a tubular halogen bulb that is {{cvt|3/8|in|mm|order=flip}} in diameter.<ref group=Note>However, a T-3, T ''hyphen'' 3, is a halogen "tube" lamp that is 3/8 of an inch in diameter with a single bi-pin base rather than a T3 ''cylindrical'' tube 3/8 of an inch in diameter with electrodes at ''opposite ends.''</ref> The designation ''MR'' means "[[multifaceted reflector|Multifaceted Reflector]]", with the number following this still corresponding to eighths of an inch in diameter of the overall bulb.<ref group=Note>Thus, an MR11 is a multifaceted reflector bulb that is 11/8 or 1 3/8 inches in diameter</ref> If a lamp has a "G" code,<ref group=Note>"G" stands for "glass"</ref> this will mean the lamp is a bipin shape and the number following the G will indicate the distance in millimeters between the pins, usually either 4, 6.35 or 10; if the G is followed by a letter "Y", then the lamp's pins are thicker than normal— thus, a G6.35 has pins that are 1&nbsp;mm in diameter but a GY6.35 has pins that are 1.3&nbsp;mm in diameter. If there is a "C" code, this represents the number of coils in the filament.<ref name="Protopopov2014">{{cite book|author=Vladimir Protopopov|title=Practical Opto-Electronics: An Illustrated Guide for the Laboratory|url=https://books.google.com/books?id=iT65BQAAQBAJ&pg=PA37|date=17 March 2014|publisher=Springer|isbn=978-3-319-04513-9|page=37}}</ref> The length (sometimes also referred to as "height") of any two-ended cylindrical bulb must be specified separately from its form factor code, usually in millimeters, as must the lamp's voltage and wattage— hence, T3 120 V 150 W 118&nbsp;mm means a double-ended tube-shaped bulb with a diameter of {{cvt|3/8|in|mm|order=flip}} that operates at 120&nbsp;V and is 150 W and that is also 118&nbsp;mm long.

An R7S is a double ended, Recessed Single Contact (RSC) linear halogen lamp, usually measuring a length of either 118&nbsp;mm or 78&nbsp;mm. Some less common lengths are 189&nbsp;mm, 254&nbsp;mm and 331&nbsp;mm. These lamps have a T3 shape on an RSC/R7S base. These can also be known as J type and T type lamps.