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. Diffuse image






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






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






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






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






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






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






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






9. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.


10. 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.






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






12. 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






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






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






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






16. 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






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






18. Stress concentration at a crack tips






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






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






21. 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.






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






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






24. 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






25. Materials change size when temperature is changed






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






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






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






29. Undergo little or no plastic deformation.






30. Second phase particles with n > glass.






31. 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






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






33. 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.






34. 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






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






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






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






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






39. 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






40. 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.






41. 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.






42. 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.






43. - 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






44. Emitted light is in phase






45. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION


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






47. 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.






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






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 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.