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






2. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






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






4. Because of ionic & covalent-type bonding.






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






6. - 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






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






8. 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






9. 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






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

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






12. Light Amplification by Stimulated Emission of Radiation






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






14. 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."






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






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






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






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






19. Occur when lots of dislocations move.






20. Materials change size when temperature is changed






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






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






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






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






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






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






27. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






28. 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






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






30. 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.






31. Diffuse image






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






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






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






35. 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






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






37. 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






38. 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






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






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






41. 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.






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






43. These materials are relatively unaffected by magnetic fields.






44. 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.






45. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






46. 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






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






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






49. 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)






50. Undergo little or no plastic deformation.