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






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






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






4. 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.






5. Because of ionic & covalent-type bonding.






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






7. 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.






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






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






10. 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)






11. 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.






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






13. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






14. Diffuse image






15. 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






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






17. 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.






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






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






20. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






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






22. Materials change size when temperature is changed






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






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






25. 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






26. Width of smallest feature obtainable on Si surface






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






28. 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.






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






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






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






32. Sigma=ln(li/lo)






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






34. 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






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






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






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






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






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






40. 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.






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






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






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






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






45. 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.






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






47. 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






48. 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.






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