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 (T _{o}).**

The formula for calculating resistance change of thermistor as a first order approximation:

ΔR = k(T – T_{o})

Where:

ΔR = Resistance Change in Thermistor as a First Order Approximation

K = Value

T = Temperature of Thermistor

T_{o} = 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

T_{o} = Ambient Temperature = 11

ΔR = k(T – T_{o})

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 – T}_{o})

Where;

K = Value

ΔR = Resistance Change in Thermistor as a First Order Approximation

T = Temperature of Thermistor

T_{o} = 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

T_{o} = Ambient Temperature = 14

K = ^{ΔR} / _{(T – T}_{o})

K = ^{22} / _{(18 – 14)}

K = ^{22} / _{4}

K = 5.5

Therefore, the **value **is **5.5.**