Question

Water has a large dielectric constant, but it is rarely used in capacitors. Explain why.

a) Water is a poor conductor.

b) Water evaporates easily.

c) Water has a low dielectric constant.

d) Water is corrosive to capacitor plates.

Answer 1

Despite its high dielectric constant, water is not commonly used in capacitors because it is a good solvent that can dissolve ions, it can corrode capacitor plates, and it evaporates easily, which affects stability and capacitor performance.

Step-by-step explanation:

Water has a large dielectric constant due to its polar character, which means that the molecules have a slight positive charge on one end and a slight negative charge on the other. This makes water easily polarizable, increasing its dielectric constant to about 80. The polarization of water molecules provides a layer of opposite charge that attracts more charge onto the plates, thus increasing the capacitance of the capacitor. However, despite its large dielectric constant, water is rarely used in capacitors because:

• Water is a good solvent, which leads to it dissolving ions that can cause electrical conduction, reducing the capacitor's effectiveness.
• Water can cause corrosion to the capacitor plates, impacting their performance and lifespan.
• Water's high evaporation rate can lead to a loss of dielectric medium, thereby affecting stability and performance.