Question

The electrical conductivity of fiber \(\underline{\hspace{2cm}}\) on increase in moisture absorption.

• A. increases
• B. decreases
• C. unchanged
• D. affected

Hint:

Think of static electricity in different weather: - Dry Winter Day: Low humidity \(\rightarrow\) fibers are dry \(\rightarrow\) high electrical resistance \(\rightarrow\) lots of static shock. - Humid Summer Day: High humidity \(\rightarrow\) fibers absorb moisture \(\rightarrow\) low electrical resistance \(\rightarrow\) static dissipates easily, no shocks. Therefore, more moisture = more conductivity.

Answer 1

The Correct Option is A

Step 1: Understand electrical conductivity in textiles. Textile fibers themselves are generally excellent electrical insulators (i.e., they have very high electrical resistance). Static electricity builds up because the charge cannot easily flow away. 
 

Step 2: Consider the role of water. Water, especially containing dissolved impurities or ions, is a much better conductor of electricity than the fiber polymer. 
 

Step 3: Analyze the effect of moisture absorption. When a fiber absorbs moisture from the atmosphere, a thin film of water forms on its surface and within its amorphous regions. This absorbed water provides a path for electrical charges to move and dissipate. The more water there is, the better this conductive path becomes. 

Conclusion: As the moisture absorption (moisture regain) of a fiber increases, its ability to conduct electricity also increases. This means its electrical resistance decreases, and it is less prone to static buildup.