Capacitance Flashcards
Define capacitance.
The charge stored per unit potential difference.
Equation linking capacitance, charge and p.d?
Q = CV
Define farad.
1F = 1 coulomb per volt
When a capacitor is in a circuit, what happens to p.d and current?
- p.d runs across the plates.
- when the p.d = e.m.f, current falls to 0.
- capacitor is fully charged.
How are capacitors arranged in series?
+ - + -
Check Notion
Total capacitance in series?
1/C = 1/C1 + 1/C2 …
Total capacitance in parallel?
C = C1 + C2 …
How are capacitors arranged in parallel?
+ with +
- with -
In parallel circuits, what is the total charge?
Q = Q1 + Q2 …
Why does work have to be done when charging a capacitor?
Electrons on negatively charged plate need to be pushed to overcome repulsion.
Electrons on positively charged plate need to be pulled away to overcome attraction.
Equations for work done by a capacitor?
W = 1/2 QV
W = 1/2 CV^2
W = 1/2 Q^2/C
Explain how the plates of a capacitor become charged in terms of the movement of electrons.
Electrons are DEPOSITED on one plate so it becomes negatively charged.
Electrons are REMOVED from one plate so it becomes positively charged.
