An electronic sensor may be represented by the block diagram in the figure below.
State the function of the processing unit.
A student designs a sensing unit for temperature change. A 
supply, a fixed resistor of resistance 
and a thermistor are available. The thermistor has resistance 
at 
and resistance 
at 
. Complete the circuit diagram below to show how the resistor and the thermistor are connected to provide an output that is greater than 
at and less than at . Mark clearly the output 
.
