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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. Ohms Law: voltage drop = current * resistance






2. Materials change size when temperature is changed






3. 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






4. Diffuse image






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






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






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






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






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






10. 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.






11. 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.






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






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






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






15. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






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






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






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

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19. 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






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






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






22. - 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






23. Different orientation of cleavage planes in grains.






24. Occur when lots of dislocations move.






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






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






27. 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






28. 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






29. 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.






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






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






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






33. 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.






34. 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






35. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






36. Because of ionic & covalent-type bonding.






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






38. Process by which metal atoms diffuse because of a potential.






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






40. 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."






41. Is analogous to toughness.






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






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






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






45. Stress concentration at a crack tips






46. Undergo little or no plastic deformation.






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






48. 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






49. Width of smallest feature obtainable on Si surface






50. Second phase particles with n > glass.