PSE 212 Test #2 Questions with Verified Answers Latest Update 2026
Three Elements Effecting Optical Properties - Answers Light Source - reflectance curve that measures the
intensity of reflected light. as a function of wavelength
Material (object) - usually the variable in the measurement.
Detector - may be an instrument; will be selectively sensitive to certain wavelengths.
Reflectance - Answers The intensity of reflected light at a particular wavelength relative to a perfect
diffuse reflecting material.
Reflectance Measurements - Answers Most measurements made in the industry are made in the blue
region of the wavelength spectrum (~450 - ~550 nm).
Subscript on R Values - Answers Indicates the number of paper sheets backing the sample sheet.
R_0 - Answers Zero indicates no backing paper sheet (just a black body)
R_Infinity - Answers Infinite number of backing sheet
R_89 - Answers Backed with 89% reflectance body
Brightness of a Paper Sheet - Answers R_Infinity at 457 nm
Kubella Munk Theory - Answers A theory that uses thin layer made up of small particles to describe the
interaction of light with a material. 2 coefficients are determined using this theory, the scattering
coefficient, S, and the absorption coefficient, K.
The scattering coefficient, S, is created by: - Answers Internal pore volume (free surface area) - more
free surface are is better for scattering.
Controlled through: structure of the paper sheet, material selection (chemical/mechanical pulps),
processing conditions (refining, wet pressing, calendaring)Refractive Index - Controlled through selection
of material; higher refractive index is a better scattering material.
Typical refractive index for paper making materials. - Answers Cellulose (Fiber Chemical) ~ 1.5
Fillers:
Calcium Carbonate ~ 1.6
Clay ~ 1.6
Titanium Dioxide ~ 2.6
Three Elements Effecting Optical Properties - Answers Light Source - reflectance curve that measures the
intensity of reflected light. as a function of wavelength
Material (object) - usually the variable in the measurement.
Detector - may be an instrument; will be selectively sensitive to certain wavelengths.
Reflectance - Answers The intensity of reflected light at a particular wavelength relative to a perfect
diffuse reflecting material.
Reflectance Measurements - Answers Most measurements made in the industry are made in the blue
region of the wavelength spectrum (~450 - ~550 nm).
Subscript on R Values - Answers Indicates the number of paper sheets backing the sample sheet.
R_0 - Answers Zero indicates no backing paper sheet (just a black body)
R_Infinity - Answers Infinite number of backing sheet
R_89 - Answers Backed with 89% reflectance body
Brightness of a Paper Sheet - Answers R_Infinity at 457 nm
Kubella Munk Theory - Answers A theory that uses thin layer made up of small particles to describe the
interaction of light with a material. 2 coefficients are determined using this theory, the scattering
coefficient, S, and the absorption coefficient, K.
The scattering coefficient, S, is created by: - Answers Internal pore volume (free surface area) - more
free surface are is better for scattering.
Controlled through: structure of the paper sheet, material selection (chemical/mechanical pulps),
processing conditions (refining, wet pressing, calendaring)Refractive Index - Controlled through selection
of material; higher refractive index is a better scattering material.
Typical refractive index for paper making materials. - Answers Cellulose (Fiber Chemical) ~ 1.5
Fillers:
Calcium Carbonate ~ 1.6
Clay ~ 1.6
Titanium Dioxide ~ 2.6
