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






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






3. 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.






4. Materials change size when temperature is changed






5. 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)






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






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






8. 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.






9. 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.






10. These materials are relatively unaffected by magnetic fields.






11. 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.






12. 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






13. Undergo extensive plastic deformation prior to failure.






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






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






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






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






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






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






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






21. Light Amplification by Stimulated Emission of Radiation






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






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






24. 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






25. Ohms Law: voltage drop = current * resistance






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






27. 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






28. Is analogous to toughness.






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






30. Occur when lots of dislocations move.






31. 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






32. Diffuse image






33. Cracks propagate along grain boundaries.






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






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






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






37. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






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

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39. A high index of refraction (n value) allows for multiple internal reactions.






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






41. 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.






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






43. Different orientation of cleavage planes in grains.






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






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






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






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






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






49. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






50. 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