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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Another optical property - Depends on the wavelength of the visible spectrum.






2. Diffuse image






3. Typical loading conditions are _____ enough to break all inter-atomic bonds






4. If a material has ________ - then the field generated by those moments must be added to the induced field.






5. Resistance to plastic deformation of cracking in compression - and better wear properties.






6. Without passing a current a continually varying magnetic field will cause a current to flow






7. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






8. A high index of refraction (n value) allows for multiple internal reactions.






9. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






10. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.






11. Materials change size when temperature is changed






12. 1. Tensile (opening) 2. Sliding 3. Tearing






13. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






14. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






15. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






16. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






17. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






18. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.






19. Metals are good conductors since their _______is only partially filled.






20. Increase temperature - increase in interatomic separation - thermal expansion






21. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






22. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






23. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






24. Different orientation of cleavage planes in grains.






25. Undergo little or no plastic deformation.






26. Occur when lots of dislocations move.






27. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






28. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






29. Emitted light is in phase






30. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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31. Dimples on fracture surface correspond to microcavities that initiate crack formation.






32. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






33. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






34. The ability of a material to absorb heat - Quantitatively: The energy required to produce a unit rise in temperature for one mole of a material.






35. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






36. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






37. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






38. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






39. Not ALL the light is refracted - SOME is reflected. Materials with a high index of refraction also have high reflectance - High R is bad for lens applications - since this leads to undesirable light losses or interference.






40. Light Amplification by Stimulated Emission of Radiation






41. For a metal - there is no ______ - only reflection






42. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






43. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






44. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






45. Undergo extensive plastic deformation prior to failure.






46. These materials are "attracted" to magnetic fields.






47. ...occurs in bcc metals but not in fcc metals.






48. Is analogous to toughness.






49. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






50. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R