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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. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






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






3. 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."






4. Undergo extensive plastic deformation prior to failure.






5. Because of ionic & covalent-type bonding.






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






7. - 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






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






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






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






11. 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






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






13. These materials are relatively unaffected by magnetic fields.






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






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. 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.






17. Sigma=ln(li/lo)






18. Stress concentration at a crack tips






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






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






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






22. Ohms Law: voltage drop = current * resistance






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






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






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






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






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






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






29. Second phase particles with n > glass.






30. 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.






31. 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)






32. Is analogous to toughness.






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






34. 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.






35. 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






36. Without passing a current a continually varying magnetic field will cause a current to flow






37. Diffuse image






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

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






40. Materials change size when temperature is changed






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






42. 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






43. 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.






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






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






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






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






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






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






50. - 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