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. 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.






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






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






4. Is analogous to toughness.






5. 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






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






7. Sigma=ln(li/lo)






8. Resistance to plastic deformation of cracking in compression - and better wear properties.






9. 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






10. Occur when lots of dislocations move.






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






12. Emitted light is in phase






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






15. 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






16. Stress concentration at a crack tips






17. 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.






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






19. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






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






21. Cracks propagate along grain boundaries.






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






23. 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)






24. Second phase particles with n > glass.






25. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






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






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






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






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






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. 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.






32. 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.






33. Width of smallest feature obtainable on Si surface






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






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






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






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






38. These materials are relatively unaffected by magnetic fields.






39. Because of ionic & covalent-type bonding.






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






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






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






43. Undergo extensive plastic deformation prior to failure.






44. Undergo little or no plastic deformation.






45. Light Amplification by Stimulated Emission of Radiation






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






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






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






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






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