Question

Sparks will occur between the plates of an air-filled capacitor at lower voltage when the air is humid than when dry. Explain why, considering the polar character of water molecules.

a) Humid air increases charge storage, causing sparks at lower voltage.

b) Humid air decreases charge storage, causing sparks at higher voltage.

c) Humid air increases capacitance, causing sparks at lower voltage.

d) Humid air decreases capacitance, causing sparks at higher voltage.

Answer 1

Sparks occur at lower voltage in humid air due to the polar character of water molecules, which align themselves with the electric field and increase the effective capacitance.

Step-by-step explanation:

The presence of water vapor in humid air increases the chances of sparks occurring between the plates of an air-filled capacitor at a lower voltage compared to when the air is dry. This can be explained by the polar character of water molecules. Water is a polar molecule, with one end having a slight positive charge and the other end having a slight negative charge. When humid air is present, the water molecules can align themselves with the electric field between the capacitor plates, increasing the effective capacitance. As a result, a spark can occur at a lower voltage.