A closed sample switch copies the input to the held node in this final-state model. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The closed switch copies the input

With the sample switch closed, the input of 4 volts becomes the held value.

Vheld=Vin=4 VV_{\text{held}} = V_{\text{in}} = 4\ \text{V}
Closed sample switchThe held node equals the input node.closed2 FV4 VV4 V+-4 V+-4 V+-4 Vsample

The capacitor stores the held voltage

The capacitance is shown as 2 farads, but this lesson claims only the final held voltage.

C=2 FVheld=4 VC = 2\ \text{F}\qquad V_{\text{held}} = 4\ \text{V}
Held capacitorThe final-state value is checked at the capacitor.closed2 FV4 VV4 V+-4 V+-4 V+-4 Vsample