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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. Light Amplification by Stimulated Emission of Radiation






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






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






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






5. Emitted light is in phase






6. Undergo extensive plastic deformation prior to failure.






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






8. 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






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






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






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






12. Materials change size when temperature is changed






13. High toughness; material resists crack propagation.






14. Undergo little or no plastic deformation.






15. Stress concentration at a crack tips






16. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






17. 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






18. 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.






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






20. Different orientation of cleavage planes in grains.






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






22. Ohms Law: voltage drop = current * resistance






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






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






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






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






27. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






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






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






30. These materials are relatively unaffected by magnetic fields.






31. 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.






32. 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."






33. - 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






34. 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






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






36. 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.






37. 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.






38. 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.






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






41. - 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






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






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






44. 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






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






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






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






50. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg