Resistance and Temperature

[Gughanath]

when is it more likely for the filament of a light bulp to break

[Integral]

It is my experience that bulbs burn out when being turned on. Of course it is impossible to tell if a bulb burns out when being turned off you will not know until you try to turn it on. It makes sense to me that when the filament is feeling large changes in temperature it experiences a maximum stress, thus is more likely to break.

I say most bulbs burn out on On/Off cycling.

[Cliff_J]

Here is probably more than you ever wanted to know and more.
http://members.misty.com/don/bulb1.html#wbt

Cliff

[PerennialII]

Here is probably more than you ever wanted to know and more.
http://members.misty.com/don/bulb1.html#wbt

Feel nearly an expert after reading that ... so essentially is the root cause concentrated thermal stresses or viscoplasticity & deformations overall due to the non-homogeneous temperature distribution (I've no idea about constitutive response of tungsten but supposedly it behaves similarly as other metals at such high relative temps?) ... I'd put a greater mark on the deformation?

[Gughanath]

wow...thank you everyone..problem solved :)