All Flashcards
How do you calculate the equivalent capacitance of capacitors in series?
Calculate the reciprocal of each capacitance, sum the reciprocals, and then take the reciprocal of the sum: .
How do you calculate the equivalent capacitance of capacitors in parallel?
Sum the individual capacitances: .
Describe the process of a capacitor charging in an RC circuit.
Initially, the uncharged capacitor allows easy charge flow, acting like a wire. As it charges, the charge on the plates increases, the current decreases, and the stored electric potential energy increases, approaching steady-state asymptotically.
Describe the process of a capacitor discharging in an RC circuit.
Charge and stored energy decrease, and current decreases over time. After a time much greater than , the circuit reaches a steady state.
What is the first step to solving a complex RC circuit problem?
Simplify the circuit by finding equivalent capacitances for series and parallel combinations.
Define equivalent capacitance.
The single capacitance that has the same effect as a combination of capacitors in a circuit.
Define time constant () in an RC circuit.
The time required for a charging capacitor to reach approximately 63% of its maximum charge or for a discharging capacitor to drop to about 37% of its initial charge. It is given by
Define capacitance.
The ability of a component or circuit to collect and store energy in the form of an electrical charge.
Define resistance.
A measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms ().
Define electromotive force ().
The voltage generated by a battery or other power source.
What is the difference between the behavior of capacitors in series vs. parallel?
Series: Same charge on each capacitor; equivalent capacitance is smaller than the smallest individual capacitance. Parallel: Same voltage across each capacitor; equivalent capacitance is the sum of individual capacitances.
Compare the current in an RC circuit at t=0 and t= during charging.
t=0: Current is at its maximum (limited only by the resistance). t=: Current is zero (capacitor is fully charged and blocks current flow).
Compare the voltage across a capacitor at t=0 and t= during charging.
t=0: Voltage across the capacitor is zero (initially uncharged). t=: Voltage across the capacitor is equal to the voltage of the source (fully charged).
Compare capacitor behavior to resistor behavior.
Capacitor: Stores energy in an electric field; opposes changes in voltage. Resistor: Dissipates energy as heat; opposes current flow.
Compare charging and discharging in an RC circuit.
Charging: Capacitor accumulates charge, voltage increases, current decreases. Discharging: Capacitor loses charge, voltage decreases, current decreases.