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






2. 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.






3. 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






4. 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.






5. Emitted light is in phase






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






7. Sigma=ln(li/lo)






8. 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.






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






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






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






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






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






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






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






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






17. 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






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

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19. Is analogous to toughness.






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






21. 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.






22. # of thermally generated electrons = # of holes (broken bonds)






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






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






25. Occur when lots of dislocations move.






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






27. - 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






28. 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






29. 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.






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






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






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

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33. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






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






35. High toughness; material resists crack propagation.






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






37. 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






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






39. 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)






40. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






41. Second phase particles with n > glass.






42. Width of smallest feature obtainable on Si surface






43. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.






44. These materials are relatively unaffected by magnetic fields.






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






46. 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.






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






48. 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






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






50. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.