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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. Resistance to plastic deformation of cracking in compression - and better wear properties.






2. Emitted light is in phase






3. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






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






5. 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.






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






7. Stress concentration at a crack tips






8. Undergo little or no plastic deformation.






9. 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.






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






11. 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.






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






13. 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






14. 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






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






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






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






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






19. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.






20. 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.






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






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






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






24. 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






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






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






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






28. Different orientation of cleavage planes in grains.






29. 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.






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






31. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






32. 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






33. 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






34. These materials are relatively unaffected by magnetic fields.






35. Light Amplification by Stimulated Emission of Radiation






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






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






38. 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






39. - 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






40. 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






41. Materials change size when temperature is changed






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






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






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






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






46. Occur when lots of dislocations move.






47. 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.






48. Sigma=ln(li/lo)






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






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