capacitance Flashcards
1
Q
capacitor
A
two conductors, isolated from each other and from their surrounding, form a capacitor. The charges on the conductors have the same magnitude q but opposite sign
2
Q
capacitance of the capacitor C =
A
C = q / V
3
Q
SI unit of capacitance
A
F(farad)
1 F = 1 C/V
4
Q
How to calculating the Capacitance
parallel-plate capacitor
A
1) use Gauss’ law to relate q and E
2) integral the E to get the potential different
V = ∫ (-to+) E ds
= E ∫ (0 to d) ds
= E d
3) q = A ε0 V/d
C = q/V = A ε0/d
5
Q
capacitors in parallel
并聯
A
C = Ca+Cb+….+Cn
6
Q
capacitors in series
A
1/C = 1/Ca + 1/Cb + …. + 1/Cn
