The expected answers were:
(a) Reactance is the opposition afforded by a pure inductor or pure capacitor to the passage of alternating current.
(b)(i) The inductive reactance,
XL = 2pfL
XL = 2p 50 x 15 x 10-3
XL = 4.71Ω
(ii) The phase angle θ = tan-1 wL/R = tan-1 XL/R = cos-1 R/Z
= tan-1 4.712 / 20
θ = 13.26o
This question was on alternating current circuit theory. This was well attempted by many candidates. Many candidates got the definition, computed correctly but got the phase-angle wrong because they could not relate it to the impedance triangle.