For a capacitor, what factor determines its capacitance besides the material?

For a capacitor, what factor determines its capacitance besides the material?

• A. The size of the conductors and their separation distance
• B. The color of the outer casing
• C. The type of AC input
• D. The ambient pressure

Answer: (C)

Capacitance comes from how much electric field the plates can support between them, which depends on geometry and the material between the plates. For a simple parallel-plate capacitor, C = ε0 εr A / d. This shows that increasing the plate area A or reducing the separation d raises the capacitance, while the dielectric constant εr of the material between the plates (the material factor) also scales C. So, besides the material, the size of the conductors and how far apart they are mainly determine capacitance. The other options don’t set the capacitance: the outer color is cosmetic, the type of AC input affects how the capacitor behaves in a circuit (impedance at a given frequency) but not the stored charge per volt, and ambient pressure typically has negligible effect in ordinary capacitors.

Capacitance comes from how much electric field the plates can support between them, which depends on geometry and the material between the plates. For a simple parallel-plate capacitor, C = ε0 εr A / d. This shows that increasing the plate area A or reducing the separation d raises the capacitance, while the dielectric constant εr of the material between the plates (the material factor) also scales C.

So, besides the material, the size of the conductors and how far apart they are mainly determine capacitance. The other options don’t set the capacitance: the outer color is cosmetic, the type of AC input affects how the capacitor behaves in a circuit (impedance at a given frequency) but not the stored charge per volt, and ambient pressure typically has negligible effect in ordinary capacitors.