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Engineering Materials

Subject : engineering
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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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. Cracks pass through grains - often along specific crystal planes.

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

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

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

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

6. 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.

7. Diffuse image

8. 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

9. Materials change size when temperature is changed

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

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

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. - 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

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

15. 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.

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

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

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

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

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

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

22. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.

23. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.

24. 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

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

26. 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

27. Second phase particles with n > glass.

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

29. 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.

30. Sigma=ln(li/lo)

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

33. High toughness; material resists crack propagation.

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

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

36. Different orientation of cleavage planes in grains.

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

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

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

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

41. 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.

42. Is analogous to toughness.

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

44. 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

45. Undergo little or no plastic deformation.

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

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

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

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

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