Question

When the frequency is decreased the impedance of a series rl circuit?

Answer 1

Z =  (R2 + (XL - XC)2 )1/2
where R is the resistance 
        XL = reactance offered by the inductor = ωL
         XC =  reactance offered by the capacitor = 1/ωC
L= inductance ,  C= capacitance


Z = (R2 + (rL - 1/rC))1/2
As frequency of the applied ac signal increase, ​ωL increases and 1/ωCdecreases.