5.4 Capacitors Flashcards
1
Q
Define
Capacitance
A
The charge stored per unit potential difference across the capacitor.
2
Q
Equation
Capacitance
A
C = Q⁄V</sup>
3
Q
Define
Farad
A
A capacitor has a capacitance of 1 farad when the charge is 1 coulomb and the p.d across it is 1 volt.
4
Q
Equation
Energy stored in a capacitor
A
E = 1⁄2QV
OR
E = 1⁄2CV2
OR
E = Q2⁄2C
4
Q
Define
Time constant, τ
A
The time constant is the time taken for the charge to have decreased to 1⁄e of the initial charge.
5
Q
Equation
Time constant, τ
A
1⁄e = 1⁄2.72 = 0.37 or 37%
