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






2. 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






3. These materials are "attracted" to magnetic fields.






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






5. Because of ionic & covalent-type bonding.






6. Emitted light is in phase






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






8. Different orientation of cleavage planes in grains.






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






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






11. 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)






12. 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






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






14. 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.






15. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






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






17. 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.






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






19. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






20. 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






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






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

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23. 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.






24. - 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






25. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






26. 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






27. 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






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






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






30. Materials change size when temperature is changed






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






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






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






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






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

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






37. 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.






38. Width of smallest feature obtainable on Si surface






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






40. Ohms Law: voltage drop = current * resistance






41. 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






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






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






44. Undergo extensive plastic deformation prior to failure.






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






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






47. 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.






48. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






49. 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.






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