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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. 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.






2. Undergo little or no plastic deformation.






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






5. Width of smallest feature obtainable on Si surface






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






7. Occur when lots of dislocations move.






8. Diffuse image






9. Cracks propagate along grain boundaries.






10. 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






11. 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






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






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






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






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






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






17. 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






18. 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.






19. Cracks pass through grains - often along specific crystal planes.






20. Undergo extensive plastic deformation prior to failure.






21. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






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






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. Materials change size when temperature is changed






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






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






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






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






29. 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.






30. 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.






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






32. Ohms Law: voltage drop = current * resistance






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






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






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






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






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






38. - 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






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






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






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






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






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






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






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






46. 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.






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






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






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






50. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)