# GATE (TF) Textile 2014 Question Paper Solution | GATE/2014/TF/22

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### What is the reflectance ratio?

Reflectance ratio in textiles refers to the ratio of the amount of light reflected from a textile material to the amount of incident light that strikes the material. It is a measure of the textile material’s ability to reflect light, and it is typically expressed as a percentage.
Reflectance ratio is an important optical property of textiles that affects their appearance, color, and perceived brightness. It is commonly measured using spectrophotometers, which are specialized instruments that can measure the amount of light reflected from a material at different wavelengths.
The reflectance ratio of a textile material depends on various factors, including its color, surface texture, and the wavelength of incident light. Different colors and surface textures of textiles may exhibit different reflectance ratios, resulting in different levels of brightness or dullness in their appearance.
Textile materials with high reflectance ratios generally appear brighter, as they reflect more light, while materials with low reflectance ratios appear darker, as they absorb more light. Reflectance ratio is an important parameter in textile industry, especially in areas such as color matching, color quality control, and textile product development, as it can impact the visual appearance and perceived quality of textiles.

### What is the formula for reflectance value?

The reflectance ratio in textiles is typically calculated using the following formula:

Reflectance ratio (%) = (Reflected light intensity / Incident light intensity) x 100
Where:
Reflected light intensity is the intensity of light reflected from the textile material, typically measured in units such as watts, lux, or photons, depending on the measurement setup and equipment used.
Incident light intensity is the intensity of light incident on the textile material, typically measured in the same units as the reflected light intensity.
The reflectance ratio is expressed as a percentage, representing the proportion of incident light that is reflected by the textile material. A higher reflectance ratio indicates that more light is reflected and less is absorbed by the textile material, resulting in a brighter appearance, while a lower reflectance ratio indicates that more light is absorbed and less is reflected, resulting in a darker appearance.
It’s important to note that the actual calculation of reflectance ratio may involve additional considerations, such as calibration of measurement equipment, correction for ambient light, and normalization for the spectral response of the human eye, depending on the specific measurement setup and standards being followed. Standardized methods, such as those defined by organizations like ASTM International or ISO (International Organization for Standardization), may be used for accurate and consistent measurement of reflectance ratio in textiles.