Test your basic knowledge |

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. 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






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






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






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






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






7. Process by which metal atoms diffuse because of a potential.






8. Undergo extensive plastic deformation prior to failure.






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






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






11. Specific heat = energy input/(mass*temperature change)






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






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






14. 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






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






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






17. Diffuse image






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






19. 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






20. 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.






21. Because of ionic & covalent-type bonding.






22. Stress concentration at a crack tips






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






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






25. 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






26. Elastic means reversible! This is not a permanent deformation.






27. Is analogous to toughness.






28. Materials change size when temperature is changed






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






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






31. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






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






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






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






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






36. 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






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






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






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






40. Light Amplification by Stimulated Emission of Radiation






41. Ohms Law: voltage drop = current * resistance






42. Undergo little or no plastic deformation.






43. 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.






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






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






46. 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)






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






48. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






49. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






50. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio