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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. 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.






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






3. 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.






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






5. 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.






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






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






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






9. 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






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

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11. Because of ionic & covalent-type bonding.






12. 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






13. 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






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






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






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






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






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






19. 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






20. 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






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






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






23. 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






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






25. 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.






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






27. Ohms Law: voltage drop = current * resistance






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






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






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






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






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






33. 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.






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






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






36. 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






37. 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






38. These materials are relatively unaffected by magnetic fields.






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






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






41. Emitted light is in phase






42. 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.






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






44. 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.






45. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






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






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






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






49. 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






50. 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.