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






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






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






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






5. Diffuse image






6. 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






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






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






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






10. 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






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






12. 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."






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






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






15. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






16. Ability to transmit a clear image - The image is clear.






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






18. Cracks propagate along grain boundaries.






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






20. Because of ionic & covalent-type bonding.






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






22. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






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






24. Light Amplification by Stimulated Emission of Radiation






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






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






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






28. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






29. Is analogous to toughness.






30. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






31. 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.






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






33. Occur when lots of dislocations move.






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

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35. 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






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






37. 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.






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






39. Different orientation of cleavage planes in grains.






40. 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






41. Undergo little or no plastic deformation.






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






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






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






45. 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






46. Sigma=ln(li/lo)






47. Emitted light is in phase






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






49. Second phase particles with n > glass.






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