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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. 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)






2. 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






3. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






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






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






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






7. Undergo little or no plastic deformation.






8. Stress concentration at a crack tips






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






10. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






11. Ohms Law: voltage drop = current * resistance






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






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






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






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






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






17. 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.






18. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






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






20. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






21. 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.






22. 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






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






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






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






26. 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.






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






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






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






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






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






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






33. Different orientation of cleavage planes in grains.






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






35. 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.






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






37. Materials change size when temperature is changed






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






39. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






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






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






42. 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.






43. 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)






44. 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






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






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






47. Width of smallest feature obtainable on Si surface






48. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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






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