Test your basic knowledge |

Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 20 minutes. 2 minutes extra for reading the instructions.
  • 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. Diffuse image






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






3. 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






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






5. 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.






6. 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.






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






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






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






10. 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






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






12. Second phase particles with n > glass.






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






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






15. Different orientation of cleavage planes in grains.






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






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






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






19. 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






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






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






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






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






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






25. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






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






27. 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."






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






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






30. 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






31. 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.






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






33. A measure of the ease with which a B field can be induced inside a material.






34. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






35. - 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






36. 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






37. Ohms Law: voltage drop = current * resistance






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






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






40. 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.






41. These materials are relatively unaffected by magnetic fields.






42. 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






43. Materials change size when temperature is changed






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






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






46. Cracks propagate along grain boundaries.






47. 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.






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






49. Is analogous to toughness.






50. Undergo little or no plastic deformation.