# Pulp & Paper Questions and Answers – Behavior of Light Rays

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This set of Pulp and Paper Multiple Choice Questions and Answers (MCQs) focuses on “Behavior of Light Rays”.

1. If a beam of light travelling in a vacuum strikes a flat surface of a transparent material at an angle of incidence φa relative to normal some of the light will be reflected at angle φr
a) True
b) False

Explanation: If a beam of light travelling in a vacuum when air is close enough strikes a flat surface of a transparent material at an angle of incidence φa relative to normal some of the light will be reflected at angle φr, and some of the light will be transmitted to the object at angle φb.

2. It is known that the angle of refraction from normal isn’t equal to the angle of the incident light from normal (φa = φr)
a) True
b) False

Explanation: It is known that the angle of reflection from normal is equal to the angle of the incident light from normal (φa = φr). It’s also known that the sin φa/sin φb, = n of the transparent material.

3. If any refracted light were to travel the same path backward the same relationship would exist, that is__________ = n.( The angle of reflection for normal is (φa = φr))
a) sin φa/cos φb
b) cos φa/sin φb
c) cosec φa/sin φb
d) sin φa/sin φb

Explanation: The incident, reflected, and refracted rays and the normal line are all in the same plane. Refracted light travels to the same path backward the same relationship would exist, that is sin φa/sin φb, = n.

4. __________ means that when light travels from a material of less index of refraction to a material of higher index of refraction, the light is bent towards the normal.
a) Reflection
b) Refraction
d) Plunge

Explanation: The refraction of light when it passes from a fast medium to a less dense medium bends the light ray toward the normal to the boundary b/w the two media. The converse is also true. na sin φa=nb sin φb.

5. With __________ it’s possible that a light ray will be reflected back into a material when striking at a higher angle.
a) TIR
b) TIM
c) CPR
d) VIBGYOR

Explanation: The complete reflection of a light ray touching an interface with a less dense medium when the angle of incidence exceeds the critical angle. It’s the phenomenon that keeps light inside glass fiber cables so that it could be transmitted large distances with relatively little loss of intensity.

6. It is known that the maximum amount of scattering results when the minimum particle dimension is about 1.5 the wavelength of the light being __________
a) Scattering
b) Shaping
c) Tyndell
d) Intensity

Explanation: Light scattering could be thought of as the deflection of a ray from a straight path, for eg. by irregularities in the propagation medium, particles, or in the interface b/w two media. This corresponds to about 0.25 jLtm, which is a common size for certain fillers.

7. __________ has very high absorbance across the spectrum and so little light is reflected or transmitted.
a) White paper
b) Grey paper
c) Black paper
d) Red paper

Explanation: Gray one has some absorbance which is nearly constant across the visible light spectrum. Gray or white is said to be achromatic (without color) and has a flat spectral reflectance curve.

8. __________ paper scatters light very little and has relatively less absorbance so that most light is transmitted through it, unless it is very thick.
a) Cellophane
b) Latex
c) Glassine
d) Plastic

Explanation: It’s a smooth and glossy paper that is air, H2O and grease resistant. An extreme eg. of this case is a clear, plastic, film, such as cellophane.

9. __________ utilizes the fact that the index of refraction of a material is a function of the wavelength of the light ray.
a) Absorption
b) Reflection
c) Refraction
d) Dispersion

Explanation: It’s the phenomenon in which the phase velocity of a wave depends on its frequency. The index of refraction of a material is often high for blue light than for the red one.

10. Light might also be ___________ as it is transmitted through a material. Reflection, refraction, and __________ of light are all very crucial in determining and predicting the optical properties of paper.
a) Absorption
b) Reflection
c) Refraction
d) Dispersion 