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






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






3. 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






4. Light Amplification by Stimulated Emission of Radiation






5. Is analogous to toughness.






6. Materials change size when temperature is changed






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






8. 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






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






10. 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.






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






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






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






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






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






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






17. Typical loading conditions are _____ enough to break all inter-atomic bonds






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

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19. Stress concentration at a crack tips






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






21. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






22. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






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






24. 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)






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






26. 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






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






28. 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






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






30. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






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






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






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






34. 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.






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






36. - 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






37. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






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






39. Diffuse image






40. 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.






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






42. Different orientation of cleavage planes in grains.






43. 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.






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






45. 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.






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






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






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






49. 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)






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