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

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






3. 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






4. Materials change size when temperature is changed






5. Width of smallest feature obtainable on Si surface






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






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






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






9. Stress concentration at a crack tips






10. Cracks propagate along grain boundaries.






11. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






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






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






14. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






15. Sigma=ln(li/lo)






16. - 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






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






18. 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






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. 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)






21. Undergo little or no plastic deformation.






22. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






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






24. Occur when lots of dislocations move.






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






26. 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.






27. Different orientation of cleavage planes in grains.






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






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






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






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






32. 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.






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






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






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






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






37. Diffuse image






38. Because of ionic & covalent-type bonding.






39. Is analogous to toughness.






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






41. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






42. 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






43. 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."






44. 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.






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






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






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






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






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






50. 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