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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • 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. 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






2. ...occurs in bcc metals but not in fcc metals.






3. These materials are relatively unaffected by magnetic fields.






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






5. 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






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






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






8. 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.






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






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






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






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






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






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






15. Ohms Law: voltage drop = current * resistance






16. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






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






18. Undergo little or no plastic deformation.






19. Occur when lots of dislocations move.






20. 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.






21. High toughness; material resists crack propagation.






22. 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)






23. Emitted light is in phase






24. 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.






25. Is analogous to toughness.






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






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






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






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






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






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






32. 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






33. 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."






34. Second phase particles with n > glass.






35. Cracks propagate along grain boundaries.






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






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






38. 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.






39. Light Amplification by Stimulated Emission of Radiation






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






41. 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






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






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






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






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

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






47. 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.






48. 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






49. 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.






50. Undergo extensive plastic deformation prior to failure.