Capacitor. This element stores charge. It can both charge and discharge during simulations. Place up to five capacitors in the simulation window. With the Select tool, you can move and rotate capacitors, and wire them to other objects. You attach wires to the capacitor's two nodes, which are indicated by the yellow rectangles in Figures 1 and 2. This element has an alternative view. |
Fig. 1 | Fig. 2
The default capacitance of the capacitor is 1,000 microfarads. You can change this capacitance in the capacitor's Properties Box, where you can set the capacitance between 1.0 microfarad and 1.0 farad. The two disabled properties are charge and voltage. You can enable these and set them separately. Remember, however, that both of these properties are highly time-dependent, as the example below illustrates. The series of figures below (best viewed in a separate window) illustrates how a capacitor can be charged during one simulation, and discharged (and recharged) in the next simulation. Note that the simulator keeps track of capacitor charge between simulation runs. Figure 3 shows the original circuit. The capacitor is starting to charge in Figure 4. The capacitor is almost fully charged in Figure 5. When fully charged, the voltage across the capacitor matches the battery voltage precisely. The simulation stops at this point.
Fig. 3 | Fig. 4 | Fig. 5
Fig. 6 | Fig. 7 | Fig. 8
During Stop mode, the leads on the capacitor are switched (Figure 6). Now the voltage drops across both the battery and capacitor. Once the second simulation starts, the bulb, subject to twice the voltage of the battery, shines much brighter (Figure 7) than it did before the capactitor charged (Figure 4). The capacitor rapidly discharges. Then it begins to recharge. By the time of Figure 8, the potential drop across the capacitor is more than half of the battery's voltage and in the opposite sense.