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






2. 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.






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






4. 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.






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






6. 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.






7. Is analogous to toughness.






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






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






10. Because of ionic & covalent-type bonding.






11. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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12. Width of smallest feature obtainable on Si surface






13. These materials are relatively unaffected by magnetic fields.






14. Sigma=ln(li/lo)






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






16. Undergo extensive plastic deformation prior to failure.






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






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






19. 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.






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






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






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






23. Occur when lots of dislocations move.






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






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






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






27. Stress concentration at a crack tips






28. 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






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






30. Undergo little or no plastic deformation.






31. 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






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






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






34. 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






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






36. Diffuse image






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






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






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






40. - 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






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






42. 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






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






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






45. 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)






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






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

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






49. 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.






50. Cracks propagate along grain boundaries.