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. Undergo extensive plastic deformation prior to failure.






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






3. - 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






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






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






6. 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






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






8. Materials change size when temperature is changed






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






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






11. 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






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






13. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






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






15. 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.






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






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






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






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






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






21. Width of smallest feature obtainable on Si surface






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






23. Is analogous to toughness.






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






25. 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






26. 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






27. Undergo little or no plastic deformation.






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






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






30. 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.






31. High toughness; material resists crack propagation.






32. Ohms Law: voltage drop = current * resistance






33. Emitted light is in phase






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






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






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






37. 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)






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






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






40. Diffuse image






41. 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.






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






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






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






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






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






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






48. 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.






49. 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






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