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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. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






2. High toughness; material resists crack propagation.






3. 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






4. Stress concentration at a crack tips






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






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






7. 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






8. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






9. Diffuse image






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






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






12. Second phase particles with n > glass.






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






14. Undergo extensive plastic deformation prior to failure.






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






16. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






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






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

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






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






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






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






23. 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






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






25. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






26. 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






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






28. - 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






29. 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.






30. 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






31. Light Amplification by Stimulated Emission of Radiation






32. Because of ionic & covalent-type bonding.






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






34. Materials change size when temperature is changed






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






36. 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.






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






38. 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."






39. Ohms Law: voltage drop = current * resistance






40. 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.






41. Process by which metal atoms diffuse because of a potential.






42. - 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






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






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






45. Cracks propagate along grain boundaries.






46. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in






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






48. 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






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






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