Lab Report

Part 1: Experimental Setup

1. What is the purpose of this experiment?

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2. List the equipment used in this experiment:

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3. Draw the circuit diagram used for this experiment:
   (Sketch the layout of the NTC thermistor, DS18B20 sensor, resistors, Arduino UNO, and the wiring on the breadboard)

Part 2: Data Collection

4. Fill in the table below with your experimental data (from 60°C to 30°C, recording resistance every 2°C drop).

Part 3: Data Analysis

7. Use the formula α=−β/T² to calculate the temperature coefficient of resistance at 60°C and 50°C.

   • α60°C​: ______________

   • α50°C​: ______________

8. Compare your experimental B-value to the theoretical B-value(B = 3950K) from the thermistor’s datasheet. What is the percentage error?

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Instructions: Complete the following questions based on the experiment you conducted. Submit your answers by the end of the week.

 Problem 1: Experimental Setup and Theory

1. Explain the working principle of an NTC thermistor and how its resistance changes with temperature.

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2. Why is it necessary to include a voltage divider circuit in this experiment?

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3. How does the Steinhart-Hart equation improve the accuracy of thermistor measurements compared to using just two temperature points?

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Problem 2: Data and Analysis

1. Using the data you collected, plot the resistance vs. temperature curve.
   (Submit a digital plot, or use graph paper to manually plot your results.)

2. Describe the shape of the resistance-temperature curve and explain why the relationship between resistance and temperature is non-linear.

3. Explain how the temperature coefficient of resistance α\alphaα varies with temperature and why this change occurs.

Problem 1: B-Value Calculation

The resistance of an NTC thermistor is measured to be 12k Ohms at 70°C and 18k Ohms at 50°C. Calculate the B-value of the thermistor using the following formula:

Where:

• T1 and T2​ are the absolute temperatures (in Kelvin) at 70°C and 50°C, respectively.

• R1​ and R2​ are the resistances at these temperatures.

(Note: Absolute temperature in Kelvin is calculated as T(K)=T(°C)+273.15

Problem 2: Alpha Calculation

Given the B-value from Problem 1, calculate the temperature coefficient of resistance α at 60°C using the formula:

Use the absolute temperature in Kelvin for T.

Problem 3: Error Analysis

The theoretical B-value of the thermistor is provided as 3950K. Compare the experimental B-value you calculated in Problem 1 with the theoretical B-value, and compute the percentage error using the following formula:

1. Worksheet (40%): Completeness and accuracy of theory, calculations, and explanations.

2. Assignment (30%): Detailed report, correct use of formulas, analysis, and discussion of results.

3. Problem Set (30%): Correctness of solutions, step-by-step calculations, and proper explanation.

Each lab group should download the Lab Report Template and fill in the relevant information as you experiment. Each group member should answer the Worksheet, Assignment, and Problem individually. Since each lab group will turn in an electronic copy of the lab report, rename the lab report template file. The naming convention is:

[Short Experiment Number]-[Student ID].PDF

Submit the Lab Report in PDf format.