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






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






3. Is analogous to toughness.






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






5. Increase temperature - no increase in interatomic separation - no thermal expansion






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






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






8. Second phase particles with n > glass.






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






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






11. # of thermally generated electrons = # of holes (broken bonds)






12. Ohms Law: voltage drop = current * resistance






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






14. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






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






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






17. 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.






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

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19. 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






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






21. Sigma=ln(li/lo)






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






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






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






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






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






27. 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






28. 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.






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






30. High toughness; material resists crack propagation.






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






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






33. Light Amplification by Stimulated Emission of Radiation






34. 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."






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






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






37. 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.






38. These materials are relatively unaffected by magnetic fields.






39. 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






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






41. 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






42. Undergo extensive plastic deformation prior to failure.






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






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






45. Undergo little or no plastic deformation.






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






47. 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.






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






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






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