In Fig. 30-60, ? = 129 V, R1 = 7.67 ?, R2 = 29.0 ?, R3 = 36.4 Ohm, and L = 2.36
ID: 1699093 • Letter: I
Question
In Fig. 30-60, ? = 129 V, R1 = 7.67 ?, R2 = 29.0 ?, R3 = 36.4 Ohm, and L = 2.36 H. Immediately after switch S is closed, what are (a) i1 and (b) i2? (Let currents in the indicated directions have positive values and currents in the opposite directions have negative values.) A long time later, what are (c) i1 and (d) i2? The switch is then reopened. Just then, what are (e) i1 and (f) i2? A long time later, what are (g) i1 and (h) i2? Figure 30-60Explanation / Answer
129 V/(7.67+29)=3.518 A a) 3.518 A b) 3.518 A R total=R2*R3/(R2+R3)+R1=23.811 ohms--->129/23.811=5.42 A--->7.67*5.42=41.55V 129-41.55=87.45 V--->87.45/29=3.02 A c) 5.42 A d) 3.02 A e) 0 A f) 0 A g) 0 A h) 0 A at steady state, the switch is opened, i coil=129/36.2=3.544 A--->tau=L/R=2.36/(29+36.4+7.67)=0.0323 s--->iL=3.544*e^(-t/0.0323) A