P 7.4-9 The circuit shown in Figure P 7.4-9 is at steady state before the switch closes. The capacitor voltages are both zero before the switch closes (v₁(0) = v₂(0) = 0).

The current i(t) is given by

(a) Determine the capacitor voltages, v₁(t) and v₂(t), for t ≥ 0.

(b) Determine the energy stored by each capacitor 20 ms after the switch closes.

The series capacitors can be replaced by an equivalent capacitor.

(c) Determine the voltage across the equivalent capacitor, + on top, for t ≥ 0.

(d) Determine the energy stored by the equivalent capacitor 20 ms after the switch closes.

Figure P7.4-9

(a) Determine the capacitor voltages, v₁(t) and v₂(t), for t ≥ 0.

We know

So we find v(t) from

For C₁

For C₂

(b) Determine the energy stored by each capacitor 20 ms after the switch closes

Energy stored is found from

The series capacitors can be replaced by an equivalent capacitor.

(c) Determine the voltage across the equivalent capacitor, + on top, for t ≥ 0.

(d) Determine the energy stored by the equivalent capacitor 20 ms after the switch closes.

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This page last updated on April 12, 2019