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. 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.






2. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






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






4. 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






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






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






7. 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






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






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






10. Different orientation of cleavage planes in grains.






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






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






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






14. Emitted light is in phase






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






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






17. Stress concentration at a crack tips






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






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






20. 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.






21. 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






22. Because of ionic & covalent-type bonding.






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






24. High toughness; material resists crack propagation.






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






26. Width of smallest feature obtainable on Si surface






27. 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.






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






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






30. 1. Tc= critical temperature- if T>Tc not superconducting 2. Jc= critical current density - if J>Jc not superconducting 3. Hc= critical magnetic field - if H > Hc not superconducting






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






32. 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






33. 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






34. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






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






36. -> fluorescent light - electron transitions occur randomly - light waves are out of phase with each other.






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






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






39. Diffuse image






40. 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






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






42. Sigma=ln(li/lo)






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






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






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






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






48. These materials are relatively unaffected by magnetic fields.






49. 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.






50. 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