Man at B&Q wrote:
On Nov 27, 11:14 am, whisky-dave wrote:
On Monday, November 26, 2012 5:48:07 PM UTC, wrote:
Bill wrote:
In message , Andrew Gabriel
writes
In many cars nowadays, the headlamps are not user replaceable
because you have to remove other parts of the engine to get to
them. That maybe why so many cars now drive with a headlamp out.
I've been wondering whether the modern fetish for flashing lights to
say "Come On", "Thanks" and so on isn't causing lamp failures. I
thought that when you apply volts to a cold filament, there is a
sudden rush of amps.
I thought they'd made a law against that sort of thing, isn't it called Ohms law ;-)

Which bit of ohm's law do you think is being broken?

He doesn't seem to be aware that the resistance of a lamp filament
increases greatly as its temperature rises from ambient to operating
temperature.

You and I both know that this is what generates the switch on surge.

HID lamps have their own switch-on problems, of course.
--
Tciao for Now!

John.