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






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






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






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






5. High toughness; material resists crack propagation.






6. 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






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






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

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






10. 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






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






12. Sigma=ln(li/lo)






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






14. 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






15. 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






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






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






18. 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."






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






20. 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.






21. 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.






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






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






24. Diffuse image






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






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






27. - 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






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. 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)






31. 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.






32. Ohms Law: voltage drop = current * resistance






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






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






35. These materials are relatively unaffected by magnetic fields.






36. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






37. Process by which metal atoms diffuse because of a potential.






38. 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






39. Materials change size when temperature is changed






40. 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






41. Width of smallest feature obtainable on Si surface






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






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






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






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






46. 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.






47. 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






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






49. Undergo extensive plastic deformation prior to failure.






50. 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.