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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. 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






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






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






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






5. 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.






6. Second phase particles with n > glass.






7. Light Amplification by Stimulated Emission of Radiation






8. 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.






9. 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






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






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






12. Diffuse image






13. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






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






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






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






17. These materials are relatively unaffected by magnetic fields.






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






19. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






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






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






22. Cracks propagate along grain boundaries.






23. 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






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






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






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






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






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






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. High toughness; material resists crack propagation.






31. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






32. 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)






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






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






35. 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.






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






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






38. 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






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






40. 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.






41. 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.






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






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






44. 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






45. 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






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






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






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






49. Because of ionic & covalent-type bonding.






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