Test your basic knowledge |

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. 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






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






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






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






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






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






7. 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.






8. Stress concentration at a crack tips






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






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






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






12. 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.






13. 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






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






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






16. 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






17. 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.






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. Emitted light is in phase






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






21. 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)






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






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






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






25. Occur when lots of dislocations move.






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






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






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






29. Light Amplification by Stimulated Emission of Radiation






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






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






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






33. 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






34. Because of ionic & covalent-type bonding.






35. 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






36. 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.






37. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






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






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






40. Width of smallest feature obtainable on Si surface






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






42. 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."






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






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






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






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






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






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






49. Dimples on fracture surface correspond to microcavities that initiate crack formation.






50. Sigma=ln(li/lo)