Question

Describe the working of capacitor with a neat sketch.

Answer 1

Working of Capacitor: When we connect a battery (DC Voltage Source) across the capacitor, one plate (plate-I) gets attached to the positive terminal and another plate (plate-II) to the negative terminal of the battery. Now, the potential of that battery is applied across that capacitor. In this situation, the electrons from plate-I are attracted towards positive terminal of battery. When electrons move from plate-I, the net charge on plate-I becomes positive. The electrons received at positive terminal are then sent to plate-II. This work is done by the battery, hence its energy is transferred to the capacitor. The plate-II becomes negatively charged since it receives negatively charged electrons. Thus the current (flow of electrons) is observed external to the capacitor and not through the dielectric material between the plates. An electric field appears across the capacitor. As time passes, plate-I becomes more & more positively charged by losing its electrons, whereas plate-II becomes more & more negatively charged by accepting the electrons from the battery. After some time, the capacitor holds maximum amount of charge as per its capacitance with respect to this voltage. This time span is called charging time of this capacitor. After disconnecting the battery from this capacitor, the two plates hold positive and negative charges for a certain time. Thus the charged capacitor acts as a source electrical energy.