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






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






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






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






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






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






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






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






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






10. Occur when lots of dislocations move.






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






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






13. 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)






14. 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






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






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






17. 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






18. 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.






19. 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






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






21. Diffuse image






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






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






24. 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






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






26. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






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






28. 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.






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






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






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






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






33. Resistance to plastic deformation of cracking in compression - and better wear properties.






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






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






36. 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.






37. Light Amplification by Stimulated Emission of Radiation






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






40. 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






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






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


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






44. 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.






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






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


47. 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






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






49. 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.






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