Test your basic knowledge |

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






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






3. 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






4. Diffuse image






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. 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.






7. 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.






8. 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






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






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






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






12. 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






13. Stress concentration at a crack tips






14. 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.






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






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






17. 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






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






19. 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






20. Undergo extensive plastic deformation prior to failure.






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






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






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






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






25. Cracks propagate along grain boundaries.






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






27. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






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






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






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

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31. Light Amplification by Stimulated Emission of Radiation






32. Sigma=ln(li/lo)






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






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






35. 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






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






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






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






39. Occur when lots of dislocations move.






40. Width of smallest feature obtainable on Si surface






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






42. Materials change size when temperature is changed






43. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






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






45. Different orientation of cleavage planes in grains.






46. 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






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






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






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






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