Parallel-Plate Capacitance
Parallel-Plate Capacitance
A capacitor’s ability to store charge per volt is set by its plate area, gap and the dielectric between the plates.
The capacitance is C = ε₀·A/d. where ε₀ is the permittivity, A the plate area and d the gap.
Inputs
eps_0 := 8.854e-12 F/m=8.85e-12 A^2·s^4/kg/m^3
A := 0.02 m^2=0.02 m^2
d := 0.001 m=1 mm
Apply the parallel-plate capacitance formula.
C := eps_0·A/d=1.77e-10 A^2·s^4/kg/m^2
Results
Larger plates or a smaller gap store more charge. Inserting a dielectric multiplies the capacitance by its relative permittivity.
Assumptions & limitations
- Uniform field (gap ≪ plate size).
- Vacuum/air dielectric.
- Edge effects neglected.