6.1 - Particles - Capacitors Flashcards
What is capacitance measured in
Farads (F) = 1CV^-1
What is a capacitor
A component that stores charge between 2 separate metallic plates
What is the equation for capacitance
C = Q/V
How do capacitors act in series
When in series : 1/ctotal = 1/c1 + 1/c2 + …
Ctotal = ( 1/c1 + 1/c2 + … )^-1
How do capacitors act in parallel
Ctotal = C1 + C2 + C2 + …
What is the equation for energy stored in a capacitor
W = 1/2 QV
W = Q^2 / 2C
What affects the time taken for a capacitor to charge or discharge
- The capacitance of the capacitor
- The resistance of the circuit
What does the area under the graph of charge against pd represent
Energy stored by the capacitor
How can a capacitor be discharged
By disconnecting the power supply and connecting another components like a resistor
What is the role of a switch in discharging a capacitor
It allows the circuit to connect to a different component for discharfe
What happens to the elections on the negative plate when the power supply is disconnected
They repel each other and flow through the circuit
When does the discharge process stop
When the charges on the plate are equalized , no pd
What is a time constant
The time it takes for the charge in a capacitor falls to 37% of the initial value
What is the equation for time constant
Resistance X Capacitance
What equations are needed for charging a capacitor
Q = Q0(1-e^-t/RC)
V=V0(1-e^-t/RC)
Q0 = CV0
