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






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






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






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






5. 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.






6. Undergo extensive plastic deformation prior to failure.






7. High toughness; material resists crack propagation.






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






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






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






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






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






13. Ohms Law: voltage drop = current * resistance






14. 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.






15. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






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






17. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)






18. 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






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






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






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






22. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






23. Different orientation of cleavage planes in grains.






24. 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






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






26. 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






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






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






29. 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.






30. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






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






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

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






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






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






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






37. 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






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






39. These materials are relatively unaffected by magnetic fields.






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






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






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






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






44. Materials change size when temperature is changed






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






46. 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






47. Light Amplification by Stimulated Emission of Radiation






48. 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.






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






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