Trevor Smith wrote:

Thankyou for the replies, I didn't think the dichrioc reflector had much to
do with it as both lamps have them but when you look at the capsual the 12v

The mains halogens typically don't have dichroic reflectors and use
ordinary opaque aluminium "silvering". That is also why they project
more heat forwards.

one is a lot brighter. I just done a bit of quick maths and the 12v 50w lamp
draws 4.16 amps and the 240v 50w lamp draws 0.208 amps so I gather more amps
= more light.

Partly, more amps in this case translate to a higher filament
temperature which gives more light.

--
Cheers,

John.

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