Test your basic knowledge |

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






2. 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






3. Is analogous to toughness.






4. Metals are good conductors since their _______is only partially filled.






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






6. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






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






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






9. Width of smallest feature obtainable on Si surface






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






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






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






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






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






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






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






18. 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.






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






20. 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.






21. 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






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






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






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






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






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






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






28. 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.






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






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






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






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






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






34. 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.






35. 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






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






37. 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






38. 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.






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






40. Stress concentration at a crack tips






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






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






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






44. 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






45. 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.






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






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






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






49. Undergo little or no plastic deformation.






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