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






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






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






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






5. Is analogous to toughness.






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






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






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






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






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






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






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






13. 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






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






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






16. 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






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






18. 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.






19. 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.






20. Light Amplification by Stimulated Emission of Radiation






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






22. 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






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






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






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






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






27. 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






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






29. Sigma=ln(li/lo)






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






31. 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.






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






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






34. 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.






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






36. 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






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






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






39. 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.






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






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






42. 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.






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






44. Cracks propagate along grain boundaries.






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






46. Undergo extensive plastic deformation prior to failure.






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






48. 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






49. 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.






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