A resistor and inductor are connected in series across an ac generator. The voltage of the generator is given by V ( t ) = V 0 cos ( ω t ) , where V 0 = 120 V , ω = 120 π rad / s , R = 450 Ω , and L = 8.5 H . (a) What is the magnitude of the impedance of the L R circuit? (b) What is the amplitude of the current through the resistor? (c) What is the phase difference between the voltage and current?