# Pulp & Paper Questions and Answers – Basic Optical Tests of Paper

This set of Pulp and Paper Multiple Choice Questions and Answers (MCQs) focuses on “Basic Optical Tests of Paper”.

1. ___________ is the measure of the hue or chroma of light reflected from the surface of paper.
a) Pigment
b) Colour
c) Opacity
d) Brightness

Explanation: Colour is the measure of the hue or chroma of light reflected from the surface of paper. It cannot be easily put in numbers, and it is frequently expressed descriptively, as “red” or “blue”. Colour of paper can be expressed by a series of three numbers in the International scale (C.I.E.) system, x, y, and z.

2. ___________ is a measure of the “whiteness” of paper. These methods are not applied to coloured papers that are characterized with the tests. The ___________ is the % of diffuse reflected light from a thick pad of paper to visible light.
a) Pigment
b) Colour
c) Opacity
d) Brightness

Explanation: Brightness is a measure of the “whiteness” of paper. These methods are not applicable to coloured papers that are characterized with the tests described above. Precisely, brightness is the % of diffuse reflected light from a thick pad of paper to visible light at a wavelength of 457 nm. This brightness is designated as R(infinity).

3. What is the name of the instrument?

a) H.G. Brightness
b) L.K. Brightness
c) M.K.L. Brightness
d) P.L. Brightness

Explanation: In the G.E. brightness, the light is illuminated on the paper at a 45 degree angle and the reflected light at 0 degree’s measured. If an ultraviolet source’s utilized, the effect of fluorescent dyes, the optical brighteners, can also be measured.

4. What is the name of the instrument?

a) H.G. Brightness
b) Elrepho test
c) Opacity test
d) Colour test

Explanation: In the Elrepho test , light source diffuse and the reflected light is measured at right angle from the surface of the paper. The diffuse light source’s a sphere coated with TiO2 from which light from 2 light bulbs reflects.

5. ___________ is the ability of paper to hide or mask a colour or object in back of the sheet. A high _________ in printed paper allows us to read the front side of the page without being distracted by print images upon the back side.
a) Brightness
b) Colour
c) Opacity
d) Gloss

Explanation: Opacity is the ability of paper to hide a colour or object in back of the sheet. A high opacity in printed paper allows us to read the front side of the page without being distracted by print images upon the back side.
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6. What is the name of the hidden part?

__________= (R0) / (R) x 100%

a) TAPPI opacity
b) Printing opacity
c) Solid opacity
d) Chroma opacity

Explanation: Printing opacity is the ability of paper to mask a colour or object in back of the sheet. A high opacity in printed paper allows one to read the front side of the page.

7. What is the name of the hidden part?

__________= (R0) / (R0.89) x 100%

a) T.A.P.P.I. opacity
b) Solid opacity
c) Chroma opacity
d) Printing opacity

Explanation: T.A.P.P.I opacity is the ability of paper to hide or mask a colour or object in back of the sheet. A high opacity in printed paper allows one to read the front side.

8. ___________ is a measure of the sheen or polish of paper.
a) Opacity
b) Brightness
c) Colour
d) Gloss

Explanation: Gloss is a measure of the sheen or polish of paper. It’s measured by illuminating the paper at a very low angle and measuring the reflectance at a similar low angle.

9. __________ pulps are of especially high opacity. Fillers tend to have high indices of refraction and provide interfaces for light scattering as well. The very high index of refraction of Ti2 allows thin papers to have high opacity as in the case of bible papers.
a) Rosewood pulps
b) Groundwood pulps
c) Roughwood pulps
d) Lignin-free wood pupls

Explanation: Stone groundwood pulps are of especially high opacity. Fillers tend to have high indices of refraction and provide interfaces for light scattering as well. The very high index of refraction of Ti2allows thin papers to have high opacity as in the case of bible papers.

10. Putting a wooden stick in clear water at an angle; the stick appears to be bend at the water-air interface. What is the property we are talking about here?
a) Gloss
b) Brightness
c) Opacity
d) Illuminating

Explanation: The classic example’s putting a wooden stick in clear water at an angle; the stick appears to bend at the water-air interface. Rough, non-flat surfaces help scatter the light in all different direction.

Sanfoundry Global Education & Learning Series – Pulp and Paper.
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