Consider the following the frequency response of the impedance of a resistor component :
We know that a resistor has a parasitic capacitance and inductance due to its leads. So the impedance of the resistor = \$Z_{inductor} + \frac{Z_{resistor} \cdot Z_{capacitor}}{Z_{resistor} +Z_{capacitor}}\$.
To find this parasitic capacitance we should use the point at \$f = 1.592\cdot 10^3\$ in such a way that \$100 = \frac{1}{\omega\cdot C}\$.
So my question is, why did we equate Z=R=100 to \$\frac{1}{\omega\cdot C}\$ only?
Why not to \$Z_{inductor} + \frac{Z_{resistor} \cdot Z_{capacitor}}{Z_{resistor} +Z_{capacitor}}\$?
One more question, why did the impedance decrease after this mentioned point? According to my understanding, the impedance before this point =100=R, if the capacitor effect will be effective after this point then this effectiveness should be added to R (i.e Z= R+1/jwc) and therefore the curve should not decrease?