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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. The ability of a material to be rapidly cooled and not fracture






2. 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






3. Second phase particles with n > glass.






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






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






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






7. 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






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






9. Materials change size when temperature is changed






10. High toughness; material resists crack propagation.






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






12. These materials are relatively unaffected by magnetic fields.






13. 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






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






15. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






16. Occur when lots of dislocations move.






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






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






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






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






21. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






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






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






24. - 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






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

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26. Ohms Law: voltage drop = current * resistance






27. 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.






28. Width of smallest feature obtainable on Si surface






29. 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.






30. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






31. 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.






32. Undergo little or no plastic deformation.






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






34. 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.






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






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






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






38. 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






39. Light Amplification by Stimulated Emission of Radiation






40. 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






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






42. 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






43. 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.






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






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






46. 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.






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






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






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






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