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Resistance and Temperature

<^< Worksheet: Resistors in Parallel | Course Index | Examples: Resistance and Temperature >^>

Graph of resistance against temp
Graph showing how resistance varies with temperature

The resistance of a conductor at a temperature, t, is given by the equation:

Rt = R0(1 + αt + βt2 + γt3....)

where α, β, γ, etc., are constants and R0 is the temperature at 0°C.

The coefficients, β, γ, etc., are quite small and since we are normally only dealing with a relatively restricted temperature range (e.g., 0°C to 100°C) we can usually approximate the characteristic to a straight line law in which case, the equation simplifies to:

Rt = R0(1 + αt)

where α is known as the temperature coefficient of resistance. Some typical values for α for various materials are given in the table below. Note that α is expressed in Ω/Ω/°C or just °C.

Elementα (°C)
Platinum+0.0034
Silver+0.0038
Copper+0.0043
Iron+0.0065
Carbon-0.0005

<^< Worksheet: Resistors in Parallel | Course index | Examples: Resistance and Temperature >^>

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Page last modified on August 01, 2011, at 10:41 AM