[Physics] Can We Change the Capacitance of a Capacitor


Can we change the capacitor capacity by changing existing charge
On the plates when it is connected to the battery?

Best Answer

There are indeed voltage dependent capacitors where the capacitance is a function of applied voltage, that is, $C(v)$ where $v$ is applied voltage. Although there may be newer technology these days, there used to be dielectric materials used in capacitors made of ferroelectric materials where the applied voltage polarizes the dipoles in the dielectric thus changing the field strength and thus the capacitance. Usually these are non-linear capacitance changes. More information should be easily located via Google search on voltage dependent capacitors.

The OP question though is not as precise as needed to determine if this is valid information as an answer. In particular, "while connected to a battery" may imply fixed voltage source. Changing charge on existing plates is in fact what happens in capacitors during charging and discharging cycles. With a fully charged capacitor with applied DC voltage, no more current will flow. This means the charge accumulated in the capacitor is now fixed. To change that you change one of the following: (1) voltage, (2) capacitance via changing physical dimensions or insertion of different dielectric material or varying the dielectric material in the capacitor.

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