1. The problem statement, all variables and given/known data Ok so I have been given a diagram which if it worked should be attached. I am having a fair bit of trouble understanding it. Now I am aware that there is both electrical and conventional currents but I am confused as to whether this is electrical or conventional. I have been told that the circuit is acting as a switch which when reaches a low temperature (resistance is high) will turn the heater on (in schematic it is a lamp). I have looked at the schematic and if it was conventional current the thermistor would not play a very big role would it? It appears to make more sense if the circuit was electrical current but then again the transistor seems to be collecting at the emitter and emitting at the collector as the transistor is an NPN. If I am correct in assuming it is an electrical current, what happens along the way. I know the capacitor is stored but as you move along and get to the junction where it goes up to the transistor and keeps going straight to the thermistor, what is the voltage that the transistor is exposed to at the emitter? However if it is a conventional current, what purpose does the thermistor have? To me, it looks like to should be electrical but I am having trouble understanding if it is or if it's conventional. To follow up, where would I move the transistor if I wanted the heater (well when I move on it will be an air conditioner) to turn on when the temperature is high (resistance is low). If it is is electrical, I am thinking you swap the normal resistor with the thermistor. Thanks to anyone who can help me!. P.S. Sorry if the format isn't perfect, I am stressing and it may seem a bit jumbled.