$$ A resistor, $0\mathrm{.}900$ H inductor, and capacitor are connected in series across a voltage source that has voltage amplitude $30\mathrm{.}0$ V and an angular frequency of $250$ rad$/$s$.($a$)$ What are $,$ and at $?$ Compare to at this instant. $($b$)$What are and Compare to $.$ Explain why these two quantities are not equal.