# GATE (TF) Textile 2020 Question Paper Solution | GATE/2020/TF/55

###### Question 55 (Textile Engineering & Fibre Science)

The work of adhesion (WSL) depends on the surface tension of the liquid and the contact angle formed on a surface and is expressed as . The WSL for a given fabric and a liquid is reduced to 1/3rd of the original value after oil repellent treatment. If the measured contact angle of the untreated fabric is 60o, the percentage change in the contact angle after the treatment is __100__.

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Given in the question:

Work of adhesion(WSL)= Where, =Surface tension of the liquid
and
Let ,WSL1=1 then, WSL2=(1/3)*WSL1 (After oil treatment)

Let,measured contact angle of untreated fabric is & Measured contact angle of treated fabric is So , =60o

Percentage change in the contact angle after treatment( )=?

Calculation:

Work of adhesion(WSL)= i.e           Now,    (Answer)

###### Frequently Asked Questions | FAQs
What is surface tension explain ?

What do you mean by contact angle ?