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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. Occur when lots of dislocations move.






2. Cracks propagate along grain boundaries.






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






4. 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.






5. Sigma=ln(li/lo)






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






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






8. 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.






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






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






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






12. Width of smallest feature obtainable on Si surface






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






14. Because of ionic & covalent-type bonding.






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






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






17. 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.






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






19. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






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






21. High toughness; material resists crack propagation.






22. Wet: isotropic - under cut Dry: ansiotropic - directional






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






24. 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.






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






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






27. 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






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






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






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






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






32. 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






33. Materials change size when temperature is changed






34. 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






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

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36. 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






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






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






39. 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.






40. 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






41. For a metal - there is no ______ - only reflection






42. 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.






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






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






45. 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.






46. Emitted light is in phase






47. They are used to assess properties of ceramics & glasses.






48. 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.






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






50. These materials are "attracted" to magnetic fields.