ABSTRACT
Consider the first-order electric circuit with an inductor and resistor only shown in Figure 7.1 with the switch in closed position (including V0 in the circuit) and in open position (so that V0 is not part of the circuit). Suppose that the switch begins in the closed position so that constant voltage V0 is applied for 0 ≤ t < 1, then a step down in voltage from V0 to 0 occurs at t = 0 as the switch is opened, and thus a constant applied voltage 0 is applied for t > 1:
LI ′ +RI = { V0, 0 ≤ t < 1 0, t > 1
(7.1)
where I is the current in the circuit, L measures the inductance, and R measures the resistance, and V0 is the constant applied voltage.
