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






2. Elastic means reversible! This is not a permanent deformation.






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






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






5. 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






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






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






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






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






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






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






12. 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






13. 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.






14. 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.






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






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






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






18. Materials change size when temperature is changed






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






20. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






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






22. Emitted light is in phase






23. Is analogous to toughness.






24. - 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






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






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






27. - 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






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






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






30. 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






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






32. 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.






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






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






35. Cracks propagate along grain boundaries.






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






37. Because of ionic & covalent-type bonding.






38. 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






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






40. Sigma=ln(li/lo)






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






42. 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






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






44. 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






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






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






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






48. Ability to transmit a clear image - The image is clear.






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






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