What's the purpose of the resistor in this circuit?
jussij: Given that : V = I x RWhere: V = voltage
       I = current
       R = resistenceFor this circuit: R = VR1 +  R2
                  V = 5
                  I = 5 / (VR1 +  R2)That means the voltage at analog pin 0:  VO = 5 - I * VR1 = 5 - VR1 * 5 / (VR1 + R2)So if you did not have the R2 resistor: VO = 5 - VR1 * 5 / VR1 = 0