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






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






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






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






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






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






7. 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.






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






9. 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."






10. Undergo extensive plastic deformation prior to failure.






11. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






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






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






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






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






16. Second phase particles with n > glass.






17. 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.






18. 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.






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






20. 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






21. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






22. Different orientation of cleavage planes in grains.






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






24. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






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






26. Is analogous to toughness.






27. Materials change size when temperature is changed






28. Because of ionic & covalent-type bonding.






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






30. 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






31. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






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






33. 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






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






35. - 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






36. Light Amplification by Stimulated Emission of Radiation






37. 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.






38. 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.






39. Emitted light is in phase






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






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






42. 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






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






44. 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






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






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






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






48. 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.






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






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