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. 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.






2. Cracks propagate along grain boundaries.






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






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






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






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






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






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






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






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






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






12. 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.






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. Occur when lots of dislocations move.






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






16. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






17. 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.






18. 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






19. 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






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






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






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






23. Diffuse image






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






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






26. 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






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






28. 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






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






30. 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






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






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






33. 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.






34. - 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






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






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






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






38. Undergo extensive plastic deformation prior to failure.






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






40. 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






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






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






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






44. 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






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






46. Ohms Law: voltage drop = current * resistance






47. Is analogous to toughness.






48. Materials change size when temperature is changed






49. 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.






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