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. 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.






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






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






4. 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






5. 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






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






7. These materials are relatively unaffected by magnetic fields.






8. 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






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






10. 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.






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






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






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






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






15. 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.






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






17. 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






18. Because of ionic & covalent-type bonding.






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






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






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






22. 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






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






24. # of thermally generated electrons = # of holes (broken bonds)






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






26. Cracks propagate along grain boundaries.






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






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






29. 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.






30. 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.






31. 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)






32. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






33. 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)






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






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






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






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






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






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






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






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






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






43. 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.






44. Stress concentration at a crack tips






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






46. 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






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






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






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






50. Materials change size when temperature is changed