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






2. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






3. 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.






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






5. Materials change size when temperature is changed






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






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






8. Cracks propagate along grain boundaries.






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






10. Sigma=ln(li/lo)






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






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






13. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






14. Light Amplification by Stimulated Emission of Radiation






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






16. Second phase particles with n > glass.






17. 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.






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






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






20. 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






21. Without passing a current a continually varying magnetic field will cause a current to flow






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






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






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






25. 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






26. 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






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






28. 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.






29. 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.






30. A high index of refraction (n value) allows for multiple internal reactions.






31. Ohms Law: voltage drop = current * resistance






32. 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)






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


34. 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.






35. These materials are "attracted" to magnetic fields.






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






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






38. Is analogous to toughness.






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






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






41. 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.






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






43. High toughness; material resists crack propagation.






44. - 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






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


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






47. 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."






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






49. 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






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