Thermistors

Objectives:

• Understand how a thermistor works. • Be able to describe the relationship between resistance and temperature for a thermistor. • Be able to describe applications of thermistors.

Task 1 - Starter

Remind the person next to you:

• What is meant by current

• The units of current

• The relationship between voltage and current for a resistor.

• The relationship between voltage and current for a bulb.

• The relationship between voltage and current for a diode.

Task 2

You are going to investigate how the resistance of a thermistor changes with temperature.  Your teacher will give you a multimeter and a thermistor.  You will need to collect a beaker and some hot water.  Test the resistance of the thermistor at 10°C intervals, from 20°C to 90°C.  You will need to draw a suitable table to collect your results.

Temperature (°C) Resistance (kΩ) 20   30   40   50   60   70   80   90

Task 3

Plot a graph of your results.

• Temperature should be along the x-axis.

• Resistance should be along the y-axis.

• Both the axes should have labels and units.

• Give your graph a suitable title.

Your graph should look something like this!

Task 4

Listen carefully as your teacher shows you this presentation, and explains why a thermistor behaves like this.

Homework/Extension:

No homework this lesson.