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. 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.






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






3. Light Amplification by Stimulated Emission of Radiation






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






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






6. Is analogous to toughness.






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






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






9. Because of ionic & covalent-type bonding.






10. - 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






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






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






13. 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






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






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






16. 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






17. Cracks propagate along grain boundaries.






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






19. 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






20. Sigma=ln(li/lo)






21. Ohms Law: voltage drop = current * resistance






22. 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.






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






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






25. 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






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






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






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






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






30. 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.






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






32. 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






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






34. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






35. High toughness; material resists crack propagation.






36. 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






37. Undergo little or no plastic deformation.






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






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






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






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






42. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






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






44. 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






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






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






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






48. Stress concentration at a crack tips






49. 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."






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