Polyester fabric is lustrous, while cotton is not. Lustre depends on the way light is reflected by
the fibre and is determined by its cross-sectional shape. Lustre is an important aesthetic
property related to the reflection of light. For example, Silk is highly lustrous due to the uniform
cross-sectional area of its fibre. Lustre results from the way light are reflected from a surface.
The more lustrous a fibre the more evenly does it reflects the incident light. Thus, the cross-sectional shapes which can reflect the incident light most evenly will give a strong lustre. But, when the fibre or filament is twisted upon itself in the yarn and fabric, the incident light is not
reflected as evenly and it results in a softer lustre.
The cross-sectional shapes of various fibres are given below. Which one of the following is
most likely the cross-sectional shape of a cotton fibre?
Answers
Answer:
A
it is correct because the particles of light here reflects back
Answer:
The correct option is (C), which represents the cross-sectional shape of cotton fibre.
Explanation:
Cotton is a non-lustrous fibre which has non-uniform cross-sectional area due to which it does not evenly reflect the light and it has softer lustre. It's given that uneven reflection of light from a surface is due to their cross-sectional shape. Cotton does not have a lustrous surface and it does not reflect the light properly as described in the statement. Whereas other three cross-sectional shape shows more or less even reflection of light through their surface which means that the chance of them being lustrous is more than cotton. Therefore, the cross-sectional shape of cotton will be (C).
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