sounds like a home work question ?It is useful to design a sensor to differentiate between gasoline and diesel.
Both do not conduct electricity.
But they are very different!
Diesel is a lubricant.
Gasoline is a solvent.
There are flammable gas alarms available so they should detect petrol.A sensitive smoke alarm detector may be capable of sensing the volatile components of gasoline, which can evaporate at room temperature. Diesel is less volatile, having a boiling point greater than water.
... A good suggestion.There are flammable gas alarms available so they should detect petrol.
Don't be silly.Refractive index. But it differs little, only at the third significant digit. That's hard to do in diy.
I think it could be trivial but we don't know the constraints. Flowrate thru a small orifice at controlled temperature would do it. Or pressure drop across an orifice at a defined flowrate.From those tables, viscosity has good discernment but is not trivial to measure.