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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. 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






2. 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






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






4. Is analogous to toughness.






5. Occur when lots of dislocations move.






6. Width of smallest feature obtainable on Si surface






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






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






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






10. Ohms Law: voltage drop = current * resistance






11. Stress concentration at a crack tips






12. Cracks propagate along grain boundaries.






13. 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






14. 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






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






16. 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






17. 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.






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






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






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






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






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






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






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






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






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






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






28. 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.






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

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






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






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






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






34. 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.






35. 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.






36. Different orientation of cleavage planes in grains.






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






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






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






40. 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






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






42. Sigma=ln(li/lo)






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






44. 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.






45. Undergo little or no plastic deformation.






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






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






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






49. 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






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