In the simple AC circuit shown in Figure 33.2, R = 70.0 and v = Vmax sin wt. (a) If vR = 0.250 Vmax for

In the simple AC circuit shown in Figure 33.2, R = 70.0 Ω and ∆v = ∆Vmax sin wt.
(a) If ∆vR = 0.250 ∆Vmax for the first time at t = 0.010 0 s, what is the angular frequency of the source?
(b) What is the next value of t for which ∆vR = 0.250 ∆Vmax?