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






3. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.






4. 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






5. 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






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






7. 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






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






9. 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.






10. Occur when lots of dislocations move.






11. 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






12. 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.






13. High toughness; material resists crack propagation.






14. 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.






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






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






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






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






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






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






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






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. Width of smallest feature obtainable on Si surface






24. Increase temperature - no increase in interatomic separation - no thermal expansion






25. 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






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






27. Light Amplification by Stimulated Emission of Radiation






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






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






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






31. 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






32. Undergo extensive plastic deformation prior to failure.






33. Sigma=ln(li/lo)






34. 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






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






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






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






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






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. 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






41. 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."






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






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






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






45. 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






46. - 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






47. 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.






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






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






50. These materials are relatively unaffected by magnetic fields.







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