Resistance vs Temperature Formula, Calculator, Calculation

Change in Resistance Calculator:

Enter the reference resistance in ohms @ 20 or 25 degrees and temperature in degrees Celsius. Then press the calculate button to get the new resistance value.

Resistance @ 20 Deg: Ohms
Temperature: Amps
New Resistance: Ohms

Resistance vs Temperature

Resistance is nothing but the amount of opposition to the flow of electrons. According to Ohms Law, the resistance is equal to the ratio between the potential differences in Volts divided by the flow of current in Amps.

Also, the resistance of a wire is depending on the temperature. Here, the change in the resistance R(new)­ in ohms is equal to the wire resistance R(ref) at the 20deg times of one plus temperature co-efficient α times of the difference between conductor temperature T in deg Celsius to the reference temperature T(ref).

The formula can be written as,

R (new) = R (ref) (1 + α (T – T (ref)))

Here the temperature co-efficient α will be considered as constant and Rref is the resistance at the reference temperature.

Look at the below chart,

Temperature co-efficient chart of different material at 20deg
Temperature co-efficient chart of different material at 20deg


Let us calculate the new change in the resistance of a copper cable @ 70 deg in that the resistance at 20 degrees will be 0.13 ohms.

As per the given data, the temperature coefficient of the copper cable will be 0.004041.

T(ref) = 20 deg

T = 70 deg.

R(ref) = 0.13 ohms

Apply our formula,

R(new) = 0.13 x (1+ (0.004041 x  (70 – 20)))

R(new) = 0.1562665 ohms.

Look at the above example, the resistance of the cable is increased from 0.13 ohms to 0.156 ohms.

Significance Resistance vs Temperature:

  1. The reference resistance will be calculated @ 20 deg or 25 deg since the specific resistance will be changed as per the temperature changes.
  2. Here, when the resistance of the wire is increased with respect to the temperature means, that material is called positive temperature co-efficient. Example: Copper
  3. Such a way that, the material’s temperature is decreased means, it is called a negative temperature coefficient material. Example: Silicon, Carbon.
  4. From the above formula, the temperature co-efficient alpha is the key for changing the resistance. Hence to get the minimum alpha, we need to create metal with 100% pure range.

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