How to Calculate and Solve for Resistance of a Temperature Detector | Temperature Measuring Instruments

The image above represents resistance of a temperature detector.

To compute for resistance of a temperature detector, four essential parameters are needed and these parameters are Reference Resistance (Ro), Temperature Co-efficient of Resistivity (α), Temperature of Thermistor (T) and Ambient Temperature (To).

The formula for calculating resistance of a temperature detector:

R = Ro [1 + α(T – To)]

Where:

R = Resistance
Ro = Reference Resistance
α = Temperature Co-efficient of Resistivity
T = Temperature of Thermistor
To = Ambient Temperature

Let’s solve an example:
Find the resistance when the reference resistance is 11, the temperature co-efficient of resistivity is 13, the temperature of thermistor is 17 and the ambient temperature is 19.

This implies that;

Ro = Reference Resistance = 11
α = Temperature Co-efficient of Resistivity = 13
T = Temperature of Thermistor = 17
To = Ambient Temperature = 19

R = Ro [1 + α(T – To)]
R = 11 x [1 + 13 x (17 – 19)]
R = 11 x [1 + 13 x (-2)]
R = 11 x [1 + -26]
R = 11 x -25
R = – 275

Therefore, the resistance of temperature detector is – 275 Ω.

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How to Calculate and Solve for Relationship between Resistance and Thermistor Temperature | Temperature Measuring Instruments

The image above represents the relationship between resistance and thermistor temperature.

To compute for relationship between resistance and thermistor temperature, four essential parameters are needed and these parameters are Reference Resistance (Ro), Temperature Parameter (β), Temperature of Thermistor (T) and Ambient Temperature (To).

The formula for calculating relationship between resistance and thermistor temperature:

R = Ro eβ(1 / T – 1 / To)

Where:

R = Resistance
Ro = Reference Resistance
β = Temperature Parameter
T = Temperature of Thermistor
To = Ambient Temperature

Let’s solve an example;
Find the resistance when the reference resistance is 21, the temperature parameter is 10, the temperature of thermistor is 14 and the ambient temperature is 8.

This implies that’

Ro = Reference Resistance = 21
β = Temperature Parameter = 10
T = Temperature of Thermistor = 14
To = Ambient Temperature = 8

R = Ro eβ(1 / T – 1 / To)
R = 21 x e10 x (1 / 14 – 1 / 21)
R = 21 x e10 x (0.071 – 0.125)
R = 21 x e10 x -0.0535
R = 21 x e-0.535
R = 21 x 0.585
R = 12.29

Therefore, the relationship between resistance and thermistor temperature is 12.29 Ω.

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How to Calculate and Solve for Resistance Change of Thermistor as a First Order Approximation | Temperature Measuring Instruments

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.

Continue reading How to Calculate and Solve for Resistance Change of Thermistor as a First Order Approximation | Temperature Measuring Instruments