Question 10: Water has a large dielectric constant but it is rarely used in capacitors. Explain why?
Water has a large value of dielectric constant; 80.1 at room temperature. Still it is not used as dielectric constant in capacitors. Following are the reasons why water is not used as dielectric constant;
(i) Under an electric field, water has H+ and OH– ions. Due to the presence of ions, water may leak charge between the plates of the capacitor leading to the discharge of the capacitor.
(ii) Water may have other impurities. Also it is quite sensitive to temperature. Both these factors can affect the value of dielectric constant of water. Therefore, different volume of water may not have same dielectric constant.
Therefore, water may not be used as dielectric in capacitors.