Things you always wanted to know the answer to [Vol. 5]
Discussion
21st Century Man said:
Headlamp bulb upgrades.
How does the same specification bulb for a given configuration output 150% - 200% more light and top the group tests?
A halogen H4 12v 60/55w is just that, so where does all that extra punch come from?
Light output and power consumption are two different things?How does the same specification bulb for a given configuration output 150% - 200% more light and top the group tests?
A halogen H4 12v 60/55w is just that, so where does all that extra punch come from?
That why a 6w LED can output the same light as a 60w filament.
21st Century Man said:
The LED comparison I understand, but one halogen H4 over another halogen H4?
I'm guessing higher quality components, lower resistance wire, more efficient reflectors, better woosits and thingummies, run at a higher temperature maybe. There could be any number of variables that mean that the better one turns more of that electrical energy into emitted light. 98elise said:
21st Century Man said:
Headlamp bulb upgrades.
How does the same specification bulb for a given configuration output 150% - 200% more light and top the group tests?
A halogen H4 12v 60/55w is just that, so where does all that extra punch come from?
Light output and power consumption are two different things?How does the same specification bulb for a given configuration output 150% - 200% more light and top the group tests?
A halogen H4 12v 60/55w is just that, so where does all that extra punch come from?
That why a 6w LED can output the same light as a 60w filament.
Other sources quote typical light yields of around 16 lumens/watt for 120V incandescent lamps versus 100 lumens/watt for white LEDs.
But filament design is crucial. Single coil filaments are many times more efficient than straight wire because the envelope of non-moving, stagnant gas surrounding the filament (called the Langmuir sheath) is much greater and for multiple coil (coiled coil) filaments the same effect is greater again, which provides a bigger insulating layer around the filament, because the spacing between coils is less than the size of the Langmuir sheath. This allows the filament to run much higher temperatures locally without radiating so much heat away, so light emission is improved and the lamp as a whole is cooler in operation.
There are now triple coiled filaments available which are very effective as the filament element is so small that the lamp is effectively a point-source. These can be used in high output car bulbs, but are more usual in things like searchlights as moving the reflector gives excellent focus control. This is where I came across them as they are used in Francis swivel searchlights on Lifeboats. In a car headlight they require very specialised reflector design which is why LED replacement lamps can't be used with the same reflector. The downside is they are prone to arcing failure. When they go, they go with a bang.
boyse7en said:
Do all mammals have more or less the same body temperature, or do some run hotter or cooler? Is a Blue Whale's core temperature lower than an Elephant's? Does a vet need to have a big chart showing the internal temps of everything from gerbils to giraffes?
A chart showing Aardvarks to Zebras would be more useful 
Cotty said:
StevieBee said:
Some years back the Honda / BAR F1 team attempted (and IIRC) succeeded in breaking the land-speed record for a wheel-driven car (as apposed to the jet-propelled cars), using an adapted F1 car. The principle change was to aero, removing the wings but retaining just enough 'ground-effect' to keep it planted. They maxed out at something like 420 kph. The factors limiting more were the tyres that have a rotational speed limit before they break apart, and the length of the desert they had to play with (11 miles). They reported that car continued to accelerate but the rate of acceleration decreased the faster it got.
420kph is about 260mph. Top fuel dragsters which are wheel driven regually pass 300mph so the tyres can take it. They also break the Honda / BAR record in only quarter of a mile not 11 miles
Edited by Cotty on Wednesday 3rd April 10:37
Error_404_Username_not_found said:
I confess I did have to look some stuff up. I knew about the stagnant gas zone from college for example but I couldn't remember what it was called.
My wife can give you 'chapter and verse' on the stagnant gas zone, should you wish.Off to read Viz now...
48k said:
Nerd augmentation alert: Ross Brawn paid Honda £1 to buy the F1 company and form Brawn GP. Brawn paid in cash and the boss of Honda still to this day has the £1 coin that Ross Brawn gave him.
So here’s a question : to complete the deal, money has to change hands. However, if the boss still has the physical £1, it then surely hasn’t been banked or paid in to Honda. So the deal is incomplete right? (I assume the £1 coin thing is a nice story and may be a visual gesture, but the transaction perhaps happened electronically etc)
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