Question

R1 L1 1mH 10Ω V1 C1 Figure 4 LC circuit with a resistor, an inductor, a capacitor and long time before -0, the switch is i inductor, a switch is moved to pole position positio a two-pole switch. For a n pole position B (Cl discon position A at-O. The following questions apply to this cir C1 is disconnected and uncharged). The position A, what is the c urrent in resistor, RI.(6) (a) Before the switch is moved to pole

Answer 1

Consider the circuit when the switch is at position 'B' for longtime. In this case Inductor acts as short circuit a) current in the R_1 is, I_R_1 = v_1/R_1 = 5/10 I_R_1 = 0. 5 Amps b) when the switch is moved to the position 'A' The current in the Inductor doesn't charge. So the elements are in series connection current through capacitor and Resistor are same. rightarrow I_R_1 = I_C_1 = 0. 5 Amps c) the voltage across capacitor after switch moved to A is, v_c (0^+) = 0volts and After long time capacitor is fully charged to the + 5volts Therefore v_c (0^+) = 0volts and v_c (infinity) = 5volts d) The Energy stored in the capacitor After long time is, E = 1/2 cv_c (infinity)^2 = 1/2 times 10 times 10^- 6 times 5^2 = 5 times 5^2 times 10^- 6 = 125 times 10^- 6 E =