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






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






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






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






5. Undergo little or no plastic deformation.






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






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






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






9. 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






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






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






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






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






14. 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.






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






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






17. Undergo extensive plastic deformation prior to failure.






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






19. 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.






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






21. 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.






22. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






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






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






25. Increase temperature - no increase in interatomic separation - no thermal expansion






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






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






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






29. Second phase particles with n > glass.






30. 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."






31. Diffuse image






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






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






34. 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






35. 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.






36. High toughness; material resists crack propagation.






37. Width of smallest feature obtainable on Si surface






38. 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






39. 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)






40. 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.






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

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


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






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






44. Materials change size when temperature is changed






45. Sigma=ln(li/lo)






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






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






48. 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






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






50. 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