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 be rapidly cooled and not fracture






2. 1. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






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






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






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. Emitted light is in phase






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






9. Stress concentration at a crack tips






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






11. 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






12. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






13. Different orientation of cleavage planes in grains.






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






15. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






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






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






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






19. Occur when lots of dislocations move.






20. 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






21. Width of smallest feature obtainable on Si surface






22. Ohms Law: voltage drop = current * resistance






23. Sigma=ln(li/lo)






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






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






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






27. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.






28. 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






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






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






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






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






33. Because of ionic & covalent-type bonding.






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. 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






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






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






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






39. Is analogous to toughness.






40. Diffuse image






41. 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.






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






43. High toughness; material resists crack propagation.






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


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. 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.






47. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






48. Light Amplification by Stimulated Emission of Radiation






49. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






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