Resistance and Temperature Coefficient.
The resistance of a Wire also depends on its temperature. The amount the resistance changes for every degree Celsius is
known as temperature coefficient symbolized as α measure in (1/oC).
i.
ii.
If The temperature of the wire increases and resistance increase the wire material is said to have a positive
temperature coefficient (+α)
If The temperature of the wire increases and resistance decrease the wire material is said to have a negative
temperature coefficient (-α)
To calculate the resistance of wire that experience a change in temperature the formula below is used:
Where
Ro = the initial resistance
α = temperature coefficient
ΔT = Change in temperature = Final temp. – Initial Temp.
The table to the right shows the temperature coefficient
of a few conducting materials with both positive and
negative temperature coefficient.