This type of sensor is intended to be used as a voltage divider, with the sensor resistance
at the voltage source. This provides an output which increases with gas concentration in
a circuit of minimum complexity. The other resistor also serves as a power limiting
resistor, ensuring that the power in the sensor itself never exceeds it maximum rating of
15 milliwatts. The equation for the minimum value of a load resistance L R to limit
power to a sensor resistance S R is