Temperature coefficient of materials

[Sham1989]

So I’ve nearly completed my

“City & Guilds 2365
Level 2 Diploma in Electrical Installations”

I’ve started to study for the electrical science exam and come to a point in the level 2 book where I am stuck and struggling to understand this part.

Can anyone help that isn’t going to judge me and help me as much as possible?

Thanks

 

[telectrix]

think it's to do with the fact tat resistance of conductive material rises with temperature. e.g. a tungsten filament bulb ( lamp for the pedantic) will read approx 60 ohms cold. that would equate to a current of approx 4A. but we all know the lamp is 60 watts = 1/4 A, so at the operating temperature, the resistance is roughly 16 times that of the cold resistance.

 

[westward10]

Pure metals will have positive coefficient whereas something like a ceramic will have a negative coefficient.

 

[telectrix]

and i always thought an empty beer glass was a negative coefficient. i got one now, so time for a refill.

 

[Deleted member 26818]

Temperature coefficient is the relationship of an effect on a material which changes as the temperature changes.
For instance, chemical reactions in water will take place more quickly at higher temperatures, than at lower temperatures.

With electrical science, it will as has already been said, be the relation of temperature to resistivity.

 

[static zap]

-- chemical reactions in water will take place more quickly at higher temperatures, than at lower temperatures.

Things bumping into each other more, speeds up chemistry
( Soluble aspirin in cold/warmer water)
but hinders an electric current in metals !

 

[Deleted member 26818]

Problem with materials with negative values, is if it is the resistance which causes the temperature to increase, and the increased temperature lowers the resistance.....