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EMA 3010 Exam 2 Questions And Answers
100% Guaranteed Pass.
Procedure for writing plan notation - Answer✔1. Shift coordinate system if plane passes through
origin
2. Identify intersections along x,y,z axes. A plane parallel to axis has infinity intercept, 0 index.
3. take reciprocal of intercepts
4. reduce to integers
5. enclose numbers in parentheses, using overscores for negative numbers
When written plane coordinates are enclosed by what? - Answer✔Parentheses
When writing plane coordinates how do you indicate a negative index? - Answer✔An overscore
over the number.
Linear Packing Density (LD) - Answer✔LD = (number of atoms centered on direction
vector)/(length of direction vector)
units are reciprocal length
Planar Packing Density (PD) - Answer✔PD = (number of atoms centered on plane)/(area of
plane)
units are reciprocal area
Linear Density of Aluminum - Answer✔3.5 nm(^-1)
Planar Density of (100) Iron - Answer✔1.2E19 atoms/m^2
Single Crystal - Answer✔A crystalline solid that exhibits only one orientation of arrangement
Properties vary with direction (anisotropic)
Polycrystalline - Answer✔Solids that exhibit more than one orientation
Properties may/may not vary with direction if grains are randomly oriented (isotropic)
Grains - Answer✔Regions of similar orientation
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Grain Boundaries - Answer✔The amorphous structures that separate regions of similar
orientation.
Isotropic - Answer✔Material Properties are non-directional
Anisotropic - Answer✔Material Properties are directional
X-Ray Diffraction (XRD) - Answer✔Used to characterize crystal structure, based on Bragg's
law, which relates angles corresponding to constructive interference to the interplane spacing (d).
X-Rays to Determine Crystal Structure - Answer✔Incoming X-rays diffract from crystal planes.
Measurement of critical angle Theta(c) allwos computation of planar spacing d.
d = n(gamma)/2sin(theta(c))
reflections must be in phase for a detectable signal
Diffracion - Answer✔Occurs when a wave encounters a series of regularly spaced obstacles that
are capable of scattering the wave and have spacing that are comparable in magnitude to the
wavelength
Bragg's Law - Answer✔Describes the relationship between x-ray wavelength (lambda),
interatomic spacing (d), and the angle of diffraction (theta) for constructive interference
d = n(lambda)/(2sin(theta))
If satisfied then you get a high detectable signal. Otherwise you get destructive interference and
the signal if weak or low.
Polymer - Answer✔Many of the same repeat unit
Mostly hydrocarbons
Covalent bonding
Saturated Hydrocarbons - Answer✔All bonds are single and no new atoms may be joined
without the removal of others that are already bonded
Methane: Each carbon singly bonded to four other atoms
Unsaturated Hydrocarbons - Answer✔Molecules with double and triple covalent bonds
Each C is not bonded to the maximum (4) other atoms
Possible for another atom or molecule to become attached to the original molecule.
2|Page
EMA 3010 Exam 2 Questions And Answers
100% Guaranteed Pass.
Procedure for writing plan notation - Answer✔1. Shift coordinate system if plane passes through
origin
2. Identify intersections along x,y,z axes. A plane parallel to axis has infinity intercept, 0 index.
3. take reciprocal of intercepts
4. reduce to integers
5. enclose numbers in parentheses, using overscores for negative numbers
When written plane coordinates are enclosed by what? - Answer✔Parentheses
When writing plane coordinates how do you indicate a negative index? - Answer✔An overscore
over the number.
Linear Packing Density (LD) - Answer✔LD = (number of atoms centered on direction
vector)/(length of direction vector)
units are reciprocal length
Planar Packing Density (PD) - Answer✔PD = (number of atoms centered on plane)/(area of
plane)
units are reciprocal area
Linear Density of Aluminum - Answer✔3.5 nm(^-1)
Planar Density of (100) Iron - Answer✔1.2E19 atoms/m^2
Single Crystal - Answer✔A crystalline solid that exhibits only one orientation of arrangement
Properties vary with direction (anisotropic)
Polycrystalline - Answer✔Solids that exhibit more than one orientation
Properties may/may not vary with direction if grains are randomly oriented (isotropic)
Grains - Answer✔Regions of similar orientation
1|Page
, ©BRIGHTSTARS 2024/2025 ALL RIGHTS RESERVED.
Grain Boundaries - Answer✔The amorphous structures that separate regions of similar
orientation.
Isotropic - Answer✔Material Properties are non-directional
Anisotropic - Answer✔Material Properties are directional
X-Ray Diffraction (XRD) - Answer✔Used to characterize crystal structure, based on Bragg's
law, which relates angles corresponding to constructive interference to the interplane spacing (d).
X-Rays to Determine Crystal Structure - Answer✔Incoming X-rays diffract from crystal planes.
Measurement of critical angle Theta(c) allwos computation of planar spacing d.
d = n(gamma)/2sin(theta(c))
reflections must be in phase for a detectable signal
Diffracion - Answer✔Occurs when a wave encounters a series of regularly spaced obstacles that
are capable of scattering the wave and have spacing that are comparable in magnitude to the
wavelength
Bragg's Law - Answer✔Describes the relationship between x-ray wavelength (lambda),
interatomic spacing (d), and the angle of diffraction (theta) for constructive interference
d = n(lambda)/(2sin(theta))
If satisfied then you get a high detectable signal. Otherwise you get destructive interference and
the signal if weak or low.
Polymer - Answer✔Many of the same repeat unit
Mostly hydrocarbons
Covalent bonding
Saturated Hydrocarbons - Answer✔All bonds are single and no new atoms may be joined
without the removal of others that are already bonded
Methane: Each carbon singly bonded to four other atoms
Unsaturated Hydrocarbons - Answer✔Molecules with double and triple covalent bonds
Each C is not bonded to the maximum (4) other atoms
Possible for another atom or molecule to become attached to the original molecule.
2|Page
