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






2. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






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






4. A measure of the ease with which a B field can be induced inside a material.






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






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






8. 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.






9. Cracks propagate along grain boundaries.






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






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






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






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






14. Undergo little or no plastic deformation.






15. 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






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






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






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






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






20. Width of smallest feature obtainable on Si surface






21. 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."






22. 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)






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






24. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






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






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






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






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






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






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






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






33. High toughness; material resists crack propagation.






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






35. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






36. 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.






37. Because of ionic & covalent-type bonding.






38. 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.






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






40. 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.






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






42. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






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






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






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






46. Different orientation of cleavage planes in grains.






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






48. 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






49. Is analogous to toughness.






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