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






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






3. 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






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






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






6. 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.






7. 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."






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






9. 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






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






11. Materials change size when temperature is changed






12. 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






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






14. 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






15. Emitted light is in phase






16. Ohms Law: voltage drop = current * resistance






17. - 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






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






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






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






21. Different orientation of cleavage planes in grains.






22. 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.






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






24. 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.






25. Is analogous to toughness.






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

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27. 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.






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






29. Occur when lots of dislocations move.






30. 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






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






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






33. 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






34. These materials are relatively unaffected by magnetic fields.






35. 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






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






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






38. Stress concentration at a crack tips






39. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






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






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






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






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






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






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






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






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






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






49. - 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






50. 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.