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






2. 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






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






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






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






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






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






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

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






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






11. 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






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






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






14. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






15. Emitted light is in phase






16. Undergo little or no plastic deformation.






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






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






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






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






21. 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.






22. 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)






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






24. 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






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






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






27. Different orientation of cleavage planes in grains.






28. 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.






29. Ohms Law: voltage drop = current * resistance






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






31. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






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






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






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






35. Diffuse image






36. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






37. - 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






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






39. 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






40. 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)






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






42. 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






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






44. 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.






45. - 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






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






47. 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






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






49. Occur when lots of dislocations move.






50. Light Amplification by Stimulated Emission of Radiation