An AC circuit is being driven by a source with an amplitude of $14\mathrm{.}3$ V and an angular frequency of $15$ Hz$.$ The circuit is an LRC series circuit with L$=1\mathrm{.}8$ H$,$ R$=45,$ and C$=2\mathrm{.}2$ mF$.$ What is the phase difference by which the current leads the voltage? Answer in radians, and include a negative sign if the current is actually lagging behind the voltage