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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. Occur when lots of dislocations move.






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






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






4. Stress concentration at a crack tips






5. 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.






6. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






7. 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






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






9. Sigma=ln(li/lo)






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






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






12. Undergo little or no plastic deformation.






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






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






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






16. 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."






17. 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.






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






19. 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






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






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






22. 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






23. Wet: isotropic - under cut Dry: ansiotropic - directional






24. 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






25. 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






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






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






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






29. Because of ionic & covalent-type bonding.






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






31. Light Amplification by Stimulated Emission of Radiation






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






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






34. Diffuse image






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






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

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37. 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






38. Cracks propagate along grain boundaries.






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






40. 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






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






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






43. These materials are relatively unaffected by magnetic fields.






44. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






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






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






47. High toughness; material resists crack propagation.






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






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






50. 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.