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






2. Diffuse image






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






4. 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






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






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






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






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






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






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






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






12. Ohms Law: voltage drop = current * resistance






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






14. Sigma=ln(li/lo)






15. 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






16. - 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






17. Emitted light is in phase






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






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






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. Width of smallest feature obtainable on Si surface






23. Undergo extensive plastic deformation prior to failure.






24. 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.






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






26. 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






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






28. 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."






29. Becomes harder (more strain) to stretch (elongate)






30. Is analogous to toughness.






31. Occur when lots of dislocations move.






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






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






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






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






36. Stress concentration at a crack tips






37. Light Amplification by Stimulated Emission of Radiation






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






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






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






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






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






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






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






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






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






47. 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






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






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






50. Because of ionic & covalent-type bonding.