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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. Is analogous to toughness.






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






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






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

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5. 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






6. Emitted light is in phase






7. Materials change size when temperature is changed






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






9. - 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






10. 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






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






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






13. Second phase particles with n > glass.






14. 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






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






16. 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.






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






18. 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.






19. 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.






20. 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.






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






22. Width of smallest feature obtainable on Si surface






23. These materials are relatively unaffected by magnetic fields.






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






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






26. 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)






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






28. Undergo extensive plastic deformation prior to failure.






29. 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






30. Cracks pass through grains - often along specific crystal planes.






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






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






34. 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






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






36. 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.






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






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






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






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






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






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






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






44. 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






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






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






47. Diffuse image






48. 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.






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






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

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