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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. Increase temperature - increase in interatomic separation - thermal expansion






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






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






4. Occur when lots of dislocations move.






5. 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.






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






7. - 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






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






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






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






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






12. 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






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






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






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






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






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






18. 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.






19. 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






20. Undergo little or no plastic deformation.






21. 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.






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






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






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






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






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






27. Elastic means reversible! This is not a permanent deformation.






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






29. 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.






30. 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.






31. Light Amplification by Stimulated Emission of Radiation






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






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






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






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






36. 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.






37. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






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






39. Diffuse image






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






41. 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."






42. 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






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






44. 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






45. Cracks propagate along grain boundaries.






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

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47. 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






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






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

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