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. Sigma=ln(li/lo)






2. 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.






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






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






5. Is analogous to toughness.






6. Second phase particles with n > glass.






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






8. Light Amplification by Stimulated Emission of Radiation






9. Not ALL the light is refracted - SOME is reflected. Materials with a high index of refraction also have high reflectance - High R is bad for lens applications - since this leads to undesirable light losses or interference.






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






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






12. - 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






13. 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






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






15. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






16. Stress concentration at a crack tips






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






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






19. 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






20. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






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






22. 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






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






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






25. These materials are relatively unaffected by magnetic fields.






26. 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)






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






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






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






30. - 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






31. 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.






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






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






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






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






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






37. 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.






38. 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






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






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






41. Undergo little or no plastic deformation.






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






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






44. 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)






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






47. Ohms Law: voltage drop = current * resistance






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






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






50. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant