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






2. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






3. 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.






4. 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






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






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






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






8. Sigma=ln(li/lo)






9. 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.






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






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






12. 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.






13. 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






14. 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.






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






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






17. 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






18. Is analogous to toughness.






19. 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






20. 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






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






22. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






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






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






25. - 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






26. 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.






27. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.






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






29. 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.






30. High toughness; material resists crack propagation.






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






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






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






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






35. Cracks propagate along grain boundaries.






36. Ohms Law: voltage drop = current * resistance






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






38. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






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






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






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






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

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


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






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. Occur when lots of dislocations move.






46. 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.






47. 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)






48. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






49. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






50. 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