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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. Ohms Law: voltage drop = current * resistance






2. 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.






3. 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.






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






5. 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






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






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






8. These materials are relatively unaffected by magnetic fields.






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






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






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






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






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






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






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






16. 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






17. 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.






18. Sigma=ln(li/lo)






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






20. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.






21. Because of ionic & covalent-type bonding.






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






23. 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.






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






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






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






27. 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)






28. 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






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






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






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






32. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






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






34. 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.






35. Diffuse image






36. 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






37. 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






38. Stress concentration at a crack tips






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






40. 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.






41. 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.






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






43. Emitted light is in phase






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






45. 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.






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






47. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






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






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






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







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