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






2. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






3. 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.






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






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






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. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






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






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






10. 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






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






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






13. Materials change size when temperature is changed






14. 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.






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






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






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






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






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






20. Light Amplification by Stimulated Emission of Radiation






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






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






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






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






25. If a material has ________ - then the field generated by those moments must be added to the induced field.






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






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






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






29. 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






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






31. Undergo little or no plastic deformation.






32. 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






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






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






35. 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.






36. 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






37. Sigma=ln(li/lo)






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






39. 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






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






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






42. 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."






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






44. 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.






45. 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






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






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






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






49. 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.






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