FIS 206 – Final Exam Study Guide and Practice Questions
simple microscope - ANS✔✔ A magnification system that uses a single lens to form an enlarged
image of an object
virtual image - ANS✔✔ an image perceived by the eye but does not actually exist; must look
through a lens to see the image (nonclipped image)
real image - ANS✔✔ an image that could be projected onto the screen (flips image)
compound microscope - ANS✔✔ A magnification system that consists of two stages of
magnification; constructed by creating a magnified real image, then magnifying the image again
to produce a focused image
ocular - ANS✔✔ the lens you look out of (one eye piece is monocular, two is binocular
objective - ANS✔✔ the switchable secondary lenses, *most important part of a microscope*
sample stage - ANS✔✔ where the sample sits, can be moved or rotated by knobs
condenser - ANS✔✔ located below stage and focuses the light on the sample
focus knob - ANS✔✔ contains coarse and fine focus, coarse moves on a larger scale than fine
light source - ANS✔✔ provides light
lens - ANS✔✔ a translucent material that bends light
,polarizing light microscopy - ANS✔✔ A magnification technique that exploits optical properties
of materials to discover details about the structure and composition of materials; uses the fact
that the anisotropic materials divide light rays into two parts to yield information about the
material (uses a polarizer- a special filter that lets light pass through only in a preferred
direction- and an analyzer- a polarizing filter that is aligned opposite the polarizer.
(Visible light vibrates in all directions, which is what causes glare. Polarized light vibrates in one
direction, such as sunglasses)
refraction - ANS✔✔ the bending of light; allows lenses to focus a beam of light onto a single
point; occurs when light passes from one medium to another when there is a difference in the
index between the two materials
refractive index - ANS✔✔ the relative speed at which light moves through a material with
respect to its speed in a vacuum
isotropic - ANS✔✔ materials that demonstrate the same optical properties in all directions such
as gases, liquids, and certain glasses or crystals
anisotropic - ANS✔✔ materials that have optical properties that vary with the orientation of the
incoming light and the optical structure of the material
birefringence - ANS✔✔ the result of the division of light into at least two rays when it passes
through certain types of material (Low birefringence shows small difference in RI, high shows a
large difference)(banding of pattern of repeating colors which is related to thickness of material)
interference colors - ANS✔✔ various colors that are diffracted depending on the wavelengths
being added and subtracted in PLM; colors are indicative of the fiber's polymer type and
molecular organization
,pleochroism - ANS✔✔ variation in a material's absorbance of light as opposed to variations in
refractive index; materials that are rotated under polarized light and change color (dichroic is
when the color is different when the sample is oriented parallel vs. perpendicular)
Michel-levy chart - ANS✔✔ gives diameter, birefringence, and retardation
Retardation - ANS✔✔ the difference in velocity of the ordinary and extraordinary rays)
comparison microscope - ANS✔✔ two compound microscopes joined by a comparison bridge;
examines two items at the side-by-side to determine if they originated from the same source or
could have been one at one point in time (ex. Bullet stria)
Polarizing Light Microscope (PLM) - ANS✔✔ addition of 2 polarizers to align light in a north-
south and an east-west direction; rotating stage to change direction of sample; used to
determine optical properties of material, isotropic vs. anisotropic, identify crystal orientation,
identify synthetic fibers and natural minerals (ex. Acrylic fibers)
Microspectrophotometer - ANS✔✔ microscope that has UV-Vis spectrophotometer attached;
used for getting UV-Vis spectra of very small, colored objects; electron transition recorded when
exposing material to UV-Vis energy ~200-700nm; not unique to material; determines exact color
of an item; used for trace evidence (ex. Fibers)
Scanning Electron Microscopy - ANS✔✔ uses electron beam to excite secondary electrons on
surface of object; emitted electrons are captured and displayed on screen; magnification up to
200,000x; object also gives off x-rays that can be used to identify elements in material;
magnified with electrons; produces a magnified image and x-rays; x-rays used to determine
elements present in the material (ex. Gunshot residues, paint)
spectroscopy - ANS✔✔ The interaction between light and matter
UV-Vis - ANS✔✔ electronic (shift of orbitals)
, Infrared - ANS✔✔ vibrational (bonds vibrate)
microwave - ANS✔✔ rotational (molecules spin/move)
radiowave - ANS✔✔ nuclear (nucleus spins)
D2 lamp/tungsten bulb, monochromator, sample holder, detector - ANS✔✔ components of a
spectrophotometer
UV-Vis spectrum - ANS✔✔ Name the spectrum
IR spectrum - ANS✔✔ Name the spectrum
Mass spectrum - ANS✔✔ Name the spectrum
sample, vacuum, ion trap/magnetic sector, detector - ANS✔✔ components of a mass
spectrometer
UV/Vis microspectrophotometry - ANS✔✔ used when evidentiary materials are too small for
instrumentation
(not confirmatory)
spectrofluorometer - ANS✔✔ used for drugs and certain pigments/dyes
infrared spectroscopy - ANS✔✔ used to unequivocally identify substances, like drugs
(confirmatory)
simple microscope - ANS✔✔ A magnification system that uses a single lens to form an enlarged
image of an object
virtual image - ANS✔✔ an image perceived by the eye but does not actually exist; must look
through a lens to see the image (nonclipped image)
real image - ANS✔✔ an image that could be projected onto the screen (flips image)
compound microscope - ANS✔✔ A magnification system that consists of two stages of
magnification; constructed by creating a magnified real image, then magnifying the image again
to produce a focused image
ocular - ANS✔✔ the lens you look out of (one eye piece is monocular, two is binocular
objective - ANS✔✔ the switchable secondary lenses, *most important part of a microscope*
sample stage - ANS✔✔ where the sample sits, can be moved or rotated by knobs
condenser - ANS✔✔ located below stage and focuses the light on the sample
focus knob - ANS✔✔ contains coarse and fine focus, coarse moves on a larger scale than fine
light source - ANS✔✔ provides light
lens - ANS✔✔ a translucent material that bends light
,polarizing light microscopy - ANS✔✔ A magnification technique that exploits optical properties
of materials to discover details about the structure and composition of materials; uses the fact
that the anisotropic materials divide light rays into two parts to yield information about the
material (uses a polarizer- a special filter that lets light pass through only in a preferred
direction- and an analyzer- a polarizing filter that is aligned opposite the polarizer.
(Visible light vibrates in all directions, which is what causes glare. Polarized light vibrates in one
direction, such as sunglasses)
refraction - ANS✔✔ the bending of light; allows lenses to focus a beam of light onto a single
point; occurs when light passes from one medium to another when there is a difference in the
index between the two materials
refractive index - ANS✔✔ the relative speed at which light moves through a material with
respect to its speed in a vacuum
isotropic - ANS✔✔ materials that demonstrate the same optical properties in all directions such
as gases, liquids, and certain glasses or crystals
anisotropic - ANS✔✔ materials that have optical properties that vary with the orientation of the
incoming light and the optical structure of the material
birefringence - ANS✔✔ the result of the division of light into at least two rays when it passes
through certain types of material (Low birefringence shows small difference in RI, high shows a
large difference)(banding of pattern of repeating colors which is related to thickness of material)
interference colors - ANS✔✔ various colors that are diffracted depending on the wavelengths
being added and subtracted in PLM; colors are indicative of the fiber's polymer type and
molecular organization
,pleochroism - ANS✔✔ variation in a material's absorbance of light as opposed to variations in
refractive index; materials that are rotated under polarized light and change color (dichroic is
when the color is different when the sample is oriented parallel vs. perpendicular)
Michel-levy chart - ANS✔✔ gives diameter, birefringence, and retardation
Retardation - ANS✔✔ the difference in velocity of the ordinary and extraordinary rays)
comparison microscope - ANS✔✔ two compound microscopes joined by a comparison bridge;
examines two items at the side-by-side to determine if they originated from the same source or
could have been one at one point in time (ex. Bullet stria)
Polarizing Light Microscope (PLM) - ANS✔✔ addition of 2 polarizers to align light in a north-
south and an east-west direction; rotating stage to change direction of sample; used to
determine optical properties of material, isotropic vs. anisotropic, identify crystal orientation,
identify synthetic fibers and natural minerals (ex. Acrylic fibers)
Microspectrophotometer - ANS✔✔ microscope that has UV-Vis spectrophotometer attached;
used for getting UV-Vis spectra of very small, colored objects; electron transition recorded when
exposing material to UV-Vis energy ~200-700nm; not unique to material; determines exact color
of an item; used for trace evidence (ex. Fibers)
Scanning Electron Microscopy - ANS✔✔ uses electron beam to excite secondary electrons on
surface of object; emitted electrons are captured and displayed on screen; magnification up to
200,000x; object also gives off x-rays that can be used to identify elements in material;
magnified with electrons; produces a magnified image and x-rays; x-rays used to determine
elements present in the material (ex. Gunshot residues, paint)
spectroscopy - ANS✔✔ The interaction between light and matter
UV-Vis - ANS✔✔ electronic (shift of orbitals)
, Infrared - ANS✔✔ vibrational (bonds vibrate)
microwave - ANS✔✔ rotational (molecules spin/move)
radiowave - ANS✔✔ nuclear (nucleus spins)
D2 lamp/tungsten bulb, monochromator, sample holder, detector - ANS✔✔ components of a
spectrophotometer
UV-Vis spectrum - ANS✔✔ Name the spectrum
IR spectrum - ANS✔✔ Name the spectrum
Mass spectrum - ANS✔✔ Name the spectrum
sample, vacuum, ion trap/magnetic sector, detector - ANS✔✔ components of a mass
spectrometer
UV/Vis microspectrophotometry - ANS✔✔ used when evidentiary materials are too small for
instrumentation
(not confirmatory)
spectrofluorometer - ANS✔✔ used for drugs and certain pigments/dyes
infrared spectroscopy - ANS✔✔ used to unequivocally identify substances, like drugs
(confirmatory)
