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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. Because of ionic & covalent-type bonding.






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






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

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






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






6. Without passing a current a continually varying magnetic field will cause a current to flow






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






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






9. Increase temperature - increase in interatomic separation - thermal expansion






10. 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)






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






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. 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."






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






15. 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






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






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






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






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






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






21. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






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






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






24. Undergo extensive plastic deformation prior to failure.






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






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






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






28. These materials are relatively unaffected by magnetic fields.






29. Sigma=ln(li/lo)






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






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






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






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






34. 1. Tensile (opening) 2. Sliding 3. Tearing






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






36. Stress concentration at a crack tips






37. 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.






38. 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






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






40. 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






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






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






43. 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.






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






45. Cracks propagate along grain boundaries.






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






47. 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.






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






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






50. Second phase particles with n > glass.