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2007-12-13 07:34:58 · 4 answers · asked by pyromaniac2617 2 in Science & Mathematics Engineering

4 answers

The previous answers mention the high 'inrush`
current experienced by the filament at start-up
and are right.
They fail to mention that the typical filament is a coil,
and that the inrush current causes an electromotive
force that mechanically stresses the filament.

2007-12-13 09:15:30 · answer #1 · answered by Irv S 7 · 1 0

At cold, the resistance of the element is much lower than hot. Therefore a much larger current occurs at switch on before the element warms up.

The larger current deteriorates the element quicker.

Sometimes this current is called inrush

2007-12-13 07:47:22 · answer #2 · answered by Poor one 6 · 0 0

It is also true that the heating and cooling cycle is hard on the filament. The tungsten filament is heated by the electricity until it is white hot, ~ 2000 degrees C. The expansion and contraction of the filament causes stresses which create cracks.

2007-12-13 08:18:40 · answer #3 · answered by Gary H 7 · 2 0

because the inrush current before it warms up are up to 16 times the current when it's incandescent.

And repeated heating and cooling is not good either

2007-12-13 08:27:07 · answer #4 · answered by Anonymous · 0 0

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