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Answered 2011-09-13 12:13:00

Positive Temperature coefficient indicates that the resistance of material INCREASES with rise in the temperature.

Resistance Temperature COefficient(RTC) is defined as increase in resistance per unit original resistance per unit rise in temperature.

Temperature Coefficient of Resistance=R2-R1/(R1*(T2-T1))

Where:

R2:Resistance at temperature T2

R1:Resistance at temperature T1

SO from formula it is clear that if resistance increases with temperature(T2-T1>0 and R2>R1) then Difference R2-R1 will be positive hence RTC will have positive value. But if with increase in temperature(T2-T1>0) resistance decreases(R2<R1) then difference R2-r1 will be negative hence RTC will be negative.

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