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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • 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. Undergo extensive plastic deformation prior to failure.






2. There is always some statistical distribution of flaws or defects.






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






4. 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






5. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






6. Stress concentration at a crack tips






7. # of thermally generated electrons = # of holes (broken bonds)






8. 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






9. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






10. Width of smallest feature obtainable on Si surface






11. These materials are relatively unaffected by magnetic fields.






12. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






13. Occur when lots of dislocations move.






14. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






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






16. Wet: isotropic - under cut Dry: ansiotropic - directional






17. Light Amplification by Stimulated Emission of Radiation






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






19. Diffuse image






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






21. A measure of the ease with which a B field can be induced inside a material.






22. 1. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






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






24. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)






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






26. 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.






27. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






28. 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.






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






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






31. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






32. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.






33. Becomes harder (more strain) to stretch (elongate)






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






35. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






36. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






37. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






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






39. Cracks propagate along grain boundaries.






40. Is analogous to toughness.






41. 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






42. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






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






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






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






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






47. 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.






48. The ability of a material to be rapidly cooled and not fracture






49. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






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