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






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






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






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






5. The size of the material changes with a change in temperature - polymers have the largest values






6. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






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






8. Diffuse image






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






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






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






12. 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






13. 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.






14. They are used to assess properties of ceramics & glasses.






15. 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.






16. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






17. 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






18. Another optical property - Depends on the wavelength of the visible spectrum.






19. Sigma=ln(li/lo)






20. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






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






22. Increase temperature - no increase in interatomic separation - no thermal expansion






23. Liquid polymer at room T - sandwiched between two sheets of glass - coated with transparent - electrically conductive film. - Character forming letters/ numbers etched on the face - Voltage applied disrupts the orientation of the rod- shaped molecule






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






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






26. 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.






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






28. Width of smallest feature obtainable on Si surface






29. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






30. Plastic means permanent! When a small load is applied - bonds stretch & planes shear. Then when the load is no longer applied - the planes are still sheared.






31. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB






32. Because of ionic & covalent-type bonding.






33. Occur when lots of dislocations move.






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






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






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






37. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.






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






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






40. Emitted light is in phase






41. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






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






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






44. Undergo extensive plastic deformation prior to failure.






45. 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.






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






47. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






48. Ability to transmit a clear image - The image is clear.






49. - 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






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