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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. Emitted light is in phase






2. 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






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






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






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






6. 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.






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






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






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






10. 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






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






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






13. 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.






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






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






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






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






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






19. Second phase particles with n > glass.






20. 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






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


22. # of thermally generated electrons = # of holes (broken bonds)






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






24. Cracks propagate along grain boundaries.






25. 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.






26. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






27. 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






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






29. Width of smallest feature obtainable on Si surface






30. 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.






31. Different orientation of cleavage planes in grains.






32. 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.






33. Diffuse image






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






35. Light Amplification by Stimulated Emission of Radiation






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






37. High toughness; material resists crack propagation.






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






39. Undergo little or no plastic deformation.






40. Occur when lots of dislocations move.






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






42. Stress concentration at a crack tips






43. 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.






44. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in






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






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






47. 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






48. 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






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






50. 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