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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. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






2. - 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






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






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






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






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






7. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






8. Is analogous to toughness.






9. These materials are relatively unaffected by magnetic fields.






10. Stress concentration at a crack tips






11. Cracks pass through grains - often along specific crystal planes.






12. High toughness; material resists crack propagation.






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






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






15. 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






16. Ohms Law: voltage drop = current * resistance






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






18. Cracks propagate along grain boundaries.






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






20. Undergo extensive plastic deformation prior to failure.






21. 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






22. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)






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






24. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.






25. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






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






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






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






29. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






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






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






32. Second phase particles with n > glass.






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






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






35. Sigma=ln(li/lo)






36. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






37. 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.






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






39. 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.






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

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






42. Width of smallest feature obtainable on Si surface






43. Occur when lots of dislocations move.






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






45. 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.






46. 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






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






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






49. 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






50. Emitted light is in phase