Investigating Charging and Discharging Capacitors Flashcards
What effect do capacitors have on a circuit?
Capacitors affect properties such as current in the circuit and potential difference across other components.
How can the charging process of a capacitor be made easier to investigate?
By including a fixed resistor in the test circuit to slow down the rate at which the capacitor charges or discharges.
What is the first step to investigate a charging capacitor?
Set up the test circuit as shown in Figure 1.
What should be recorded while the capacitor is charging?
The potential difference (p.d.) and the current over time.
When is a capacitor considered fully charged?
When the current through the ammeter is 0.
What happens to the current as a capacitor charges?
The current decreases over time.
What is the relationship between charge (Q) and potential difference (V) across a capacitor?
The charge on the capacitor is proportional to the potential difference across it.
What should be done to investigate a discharging capacitor?
Open the switch, remove the power supply, and reconnect the circuit.
What happens to the current and potential difference when a capacitor is fully discharged?
Both the current and potential difference across the plates fall to zero.
In which direction do electrons flow during the discharging of a capacitor?
From the negative plate to the positive plate.
What happens to the potential difference across the plates as charge leaves the capacitor?
The potential difference decreases.
What equation relates the change in charge (AQ) to time (At) for a discharging capacitor?
AQ = - (Q / R) At.
What is the purpose of using a spreadsheet in modeling capacitor discharge?
To demonstrate how a capacitor gradually discharges over time.
What should be included in the columns of a new spreadsheet for modeling capacitor discharge?
- Time elapsed since discharge began
- Change in charge (AQ)
- Charge remaining on the capacitor (Q).
What should be chosen for the initial charge (Q_initial) when setting up the spreadsheet?
An initial starting charge for the capacitor along with values for capacitance (C) and resistance (R).
What should the time interval (Δt) be when modeling discharge in a spreadsheet?
Significantly less than CR.
What formula should be used to calculate the change in charge (AQ) in the spreadsheet?
AQ = - (Q / R) Δt.
What is the expected outcome when plotting a graph of charge against time for a discharging capacitor?
The graph should resemble the graph for a discharging capacitor.
