It has a radius (and hence a capacitance) of 6:4£108 cm. This is so large that we can e®ectively take charge from or dump charge onto the earth without changing its electrical potential at all. Converting, the earth has a capacitance Cearth = 0:0007 Farad | enormous, but still signi ̄cantly smaller than a Farad!
Again, in CGS system, the formula of the capacitance of an isolated sphere like Earth is, \small {\color {Blue} C=R} C = R ……. (2) So, from equation- (1) and equation- (2) it is clear that the capacitance of Earth depends only on its radius. The radius of the Earth, R = 6400 km = 6.4×10 6 meter.
From the definition of capacitance, we have d V | ∆ | 0 = C A ε Q = ( parallelplate ) Note that C depends only on the geometric factors A and d. The capacitance C increases linearly with the area A since for a given potential difference ∆ V , a bigger plate can hold more charge.
• A capacitor is a device that stores electric charge and potential energy. The capacitance C of a capacitor is the ratio of the charge stored on the capacitor plates to the the potential difference between them: (parallel) This is equal to the amount of energy stored in the capacitor. The E surface. 0 is the electric field without dielectric.
The equivalent capacitance is given by plates of a parallel-plate capacitor as shown in Figure 5.10.3. Figure 5.10.3 Capacitor filled with two different dielectrics. Each plate has an area A and the plates are separated by a distance d. Compute the capacitance of the system.
The energy (measured in joules) stored in a capacitor is equal to the work required to push the charges into the capacitor, i.e. to charge it. Consider a capacitor of capacitance C, holding a charge + q on one plate and − q on the other.