Temperature Coefficient of Resistance - Meaning and calculate

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What is the temperature coefficient of resistance？

•  mention relation between resistance and temperature，Our resistance in practical application, its temperature will vary with the temperature of the working environment, which produces a working rate of change of resistance, become the resistance temperature coefficient.

•  It is usually ppm / °C (parts per million per degree Centigrade) units. resistance temperature change will have different effects on the circuit, directly affect the operation of our products, so this is a topic that has to be paid attention to.

•  The main principle is the collision result of the electron internal materials, those materials are resistance problem, when the temperature rises, the electron collision will be faster and faster, and then the temperature will be higher and higher, this is the problem.

•  Then this relationship can be calculated.

•  Now let's talk about how to calculate the results of this process.

How to calculate temperature coefficient of resistance 

•  Define temperature coefficient of resistance：The temperature of 20°C is very significant for the resistance, this number determines the change of the resistance temperature coefficient, the resistor beyond 20°C needs to be determined by a formula, which is why we see a lot of the resistance meter on the specific label temperature is 20°.

•  temperature coefficient of resistance formula

•  Each once temperature change will produce a change coefficient, usually use "α" (α) to represent the temperature coefficient of resistance, because the resistance itself will produce some changes with the change of temperature, resistance will increase with the temperature.

Under different materials temperature coefficient of resistivity 

•  Temperature coefficient of resistivity

•  The resistivity is not only related to material species, but also related to external factors such as temperature, pressure and magnetic field, let's back to the temperature coefficient of resistance, refers to when the temperature every once, the percentage of resistance increase.

•  For example, the temperature coefficient of platinum is 0.00374/℃，It is a percentage.

•  At 20℃, a 1000 ohm platinum resistance, when the temperature rises to 21℃, its resistance will become 1003.74ohm.

• So the temperature coefficient can not be ignored, which needs to be used as a very important reference, here is the common metal resistivity and its temperature coefficient.

Why is temperature coefficient of resistance negative for semiconductor

Temperature can change a lot of things, for resistance is no exception, with the rise of temperature, the concentration of electron and hole will increase, with the increase, pure semiconductor conductivity will be higher, so the resistivity of the semiconductor will increase with the rise of temperature, the semiconductor resistance temperature coefficient will is negative.