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






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






3. 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






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






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






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

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






8. 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.






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






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






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






12. Second phase particles with n > glass.






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






14. 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.






15. 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.






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






17. 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






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






19. 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






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






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






22. Because of ionic & covalent-type bonding.






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






24. 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.






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






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






27. 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.






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






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






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






31. Plastic means permanent! When a small load is applied - bonds stretch & planes shear. Then when the load is no longer applied - the planes are still sheared.






32. Undergo little or no plastic deformation.






33. 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.






34. 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






35. 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






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






37. 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






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






39. Light Amplification by Stimulated Emission of Radiation






40. Sigma=ln(li/lo)






41. Undergo extensive plastic deformation prior to failure.






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






43. 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






44. - 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






45. 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.






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






48. 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.






49. Cracks propagate along grain boundaries.






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