derive capacitance of parallel plate capacitor

Asked by Amit Agarwal | 24th Mar, 2012, 11:39: AM

Expert Answer:

Parallel plate model

Dielectric is placed between two conducting plates, each of area A and with a separation of d

.

The simplest capacitor consists of two parallel conductive plates separated by a dielectric with permittivity ? (such as air). The model may also be used to make qualitative predictions for other device geometries. The plates are considered to extend uniformly over an area A and a charge density ±? = ±Q/A exists on their surface. Assuming that the width of the plates is much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E = ?/?. The voltage is defined as the line integral of the electric field between the plates

Solving this for C = Q/V reveals that capacitance increases with area and decreases with separation

.

Answered by  | 24th Mar, 2012, 06:47: PM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.