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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. 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.






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






3. 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






4. 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.






5. 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






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






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






8. 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






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






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






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






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






13. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






14. 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.






15. - 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






16. Emitted light is in phase






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






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






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






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






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






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






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






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






25. 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.






26. Different orientation of cleavage planes in grains.






27. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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28. These materials are relatively unaffected by magnetic fields.






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






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






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






32. Undergo little or no plastic deformation.






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






34. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






35. Stress concentration at a crack tips






36. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






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






38. Second phase particles with n > glass.






39. 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.






40. Diffuse image






41. Cracks propagate along grain boundaries.






42. 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.






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






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






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






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






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






48. Materials change size when temperature is changed






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






50. Width of smallest feature obtainable on Si surface