8.39 The current in the ci rcuit in Fig. 8.3 is known to be
i = B 1e-20001 co s lS00t + B2e-20001 s in 1500t, t 2:'.: 0.
The capacitor ha s a value of 80 nF ; the initial value
of the current is 7 .5 mA ; and the initial vo lt ag e on
the capacitor is -3 0 V. Find t he va lu es of R, L , B 1,
and B 2. 8.40 Find the vo lt age a cro ss th e 80 nF ca p ac it or for th e
c ir c uit d esc rib ed in Prob le m 8.39 .A ss um e th e r efe r
en ce pol a rit y for th e ca p ac ito r v olt age is po sitive at
the upper termin a l