These change by environmental means: temperature, voltage, light ... As the current in a circuit increases, the temperature of the thermistor increases due to normal resistive heating.

This transistor switching circuit uses an npn transistor, a voltage divider (consisting of a \(5 kΩ \) resistor and thermistor) and a \(5 V\) power supply. Use the information in the table to ...

The two resistors may have fixed values or one may be an LDR, a thermistor or other input ... the resistors are connected together. The circuit of a voltage divider may be drawn with the two ...