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






2. 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






3. 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






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






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






6. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






7. These materials are relatively unaffected by magnetic fields.






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






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






10. Undergo little or no plastic deformation.






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






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






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






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






15. 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






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






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

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18. 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.






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






20. The ability of a material to be rapidly cooled and not fracture






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






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






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






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






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






26. Ohms Law: voltage drop = current * resistance






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






28. Occur when lots of dislocations move.






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






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






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






32. 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






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






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






35. Different orientation of cleavage planes in grains.






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






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






38. 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.






39. High toughness; material resists crack propagation.






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






42. 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






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






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






45. 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.






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






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






48. 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






49. Sigma=ln(li/lo)






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