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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. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)






2. 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.






3. Ohms Law: voltage drop = current * resistance






4. Stress concentration at a crack tips






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






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






7. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






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






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






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






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






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






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






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






15. 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






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






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






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






19. 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






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






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






22. Materials change size when temperature is changed






23. Different orientation of cleavage planes in grains.






24. Sigma=ln(li/lo)






25. Occur when lots of dislocations move.






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






27. Because of ionic & covalent-type bonding.






28. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






29. 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.






30. 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.






31. 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






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






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






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






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






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






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






38. Is analogous to toughness.






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






40. Cracks propagate along grain boundaries.






41. Second phase particles with n > glass.






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






43. Undergo extensive plastic deformation prior to failure.






44. 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."






45. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






46. 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.






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






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






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






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