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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. Materials change size when temperature is changed






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






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






4. 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.






5. Diffuse image






6. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






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






8. Ohms Law: voltage drop = current * resistance






9. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






10. Second phase particles with n > glass.






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






12. 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.






13. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R






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






15. 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






16. 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






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






18. 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.






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






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






21. 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.






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






23. These materials are relatively unaffected by magnetic fields.






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






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






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






27. Light Amplification by Stimulated Emission of Radiation






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






29. 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.






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






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






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






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






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

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






36. 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






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






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






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






40. - 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






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






42. 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






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






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






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






47. Width of smallest feature obtainable on Si surface






48. 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






49. 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






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