The image above represents resistance change of thermistor as a first order approximation.
To compute for resistance change of thermistor as a first order approximation, three essential parameters are needed and these parameters are Value (K), Temperature of Thermistor (T) and Ambient Temperature (To).
The formula for calculating resistance change of thermistor as a first order approximation:
ΔR = k(T – To)
Where:
ΔR = Resistance Change in Thermistor as a First Order Approximation
K = Value
T = Temperature of Thermistor
To = Ambient Temperature
Let’s solve an example;
Find the resistance change in thermistor as a first order approximation when the value is 22, the temperature of thermistor is 16 and the ambient temperature is 11.
This implies that;
K = Value = 22
T = Temperature of Thermistor = 16
To = Ambient Temperature = 11
ΔR = k(T – To)
ΔR = 22 x (16 – 11)
ΔR = 22 x 5
ΔR = 110
Therefore, the resistance change of thermistor as a first order approximation is 110 Ω.
Calculating for the Value when the Resistance Change of Thermistor as a First Order Approximation, the Temperature of Thermistor and the Ambient Temperature is Given.
K = ΔR / (T – To)
Where;
K = Value
ΔR = Resistance Change in Thermistor as a First Order Approximation
T = Temperature of Thermistor
To = Ambient Temperature
Let’s solve an example;
Find the value when the resistance change in thermistor as a first order approximation is 22, the temperature of thermistor is 18 and the ambient temperature is 14.
This implies that;
ΔR = Resistance Change in Thermistor as a First Order Approximation = 22
T = Temperature of Thermistor = 18
To = Ambient Temperature = 14
K = ΔR / (T – To)
K = 22 / (18 – 14)
K = 22 / 4
K = 5.5
Therefore, the value is 5.5.