capacitance

[akimhaneul]

Why does a decrease in distance between the plates increase the capacitance?

Also, does dielectric increase capacitance because its molecules with partial charges align with the plates, allowing the charges on the plates to be more stabilized?

Thanks!

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[theonlytycrane]

Capacitance = constant * Area (of the plates) / distance (between the plates). Decreasing the denominator increases C.

A dielectric increases total charge on the plates because the molecules with partial charges help stabilize and increase the charge buildup on the plates.

 

[akimhaneul]

Capacitance = constant * Area (of the plates) / distance (between the plates). Decreasing the denominator increases C.

A dielectric increases total charge on the plates because the molecules with partial charges help stabilize and increase the charge buildup on the plates.

Thanks but is there a more intuitive reason for why decreasing the distance increases capacitance?

 

[theonlytycrane]

In a circuit, one plate of the capacitor will hold a + charge and the other plate will hold a - charge. There is a voltage difference between the plates given by V = E * d.

Decreasing d means we're bringing the plates that hold charges closer together. Capacitors store energy in electric fields. In V = E * d, V is fixed from the battery, d decreases, so E must increase. Increasing the electric field strength is analogous to increasing the stored energy.

 

[wizzed101]

Thanks but is there a more intuitive reason for why decreasing the distance increases capacitance?

Just imagine what will happen if you move one of the plate, say 1 mile, away from the other. The capacitance will be zero! The reverse must be true.

Or that the charges on the plates are held in place by external electric fields from the opposite plates. The closer the plates, the greater the fields and subsequently, the higher capacitance.