Mid Term Test 2002 Solutions

# Mid Term Test 2002 Solutions - Engin Mater 2O03 Mid-Term...

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Engin / Mater 2O03 Mid-Term Page 1 of 6 Materials 2O03 / Engineering 2O03 Mid-Term Test (2002) Duration: 50 minutes Aids allowed: 1 page crib sheet, nominally 8½ by 11 in. McMaster standard Casio FX-991 calculator Be sure to show your work so that part marks can be awarded for incomplete answers. For multiple choice questions, marked will be deducted for incorrect answers – circle only those for which you are confident of the answer. Total marks: 60 1. [6 marks] Atomic bonding can be understood by considering how the energy of one atom changes as it approaches another. a) Draw a diagram of this energy as a function of the separation, on which you should label the bond energy and the equilibrium separation. b) List the three kinds of primary bonds found in solids and indicate for each whether the bonding is directional or not and whether it is localized or not. Ionic – non-directional, local Metallic – non-directional, non-local Covalent – directional, local Energy, U Separation r 0 Bond energy, U o

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Engin / Mater 2O03 Mid-Term Page 2 of 6 2. [6 marks] From an x-ray diffraction pattern one finds a strong peak for x-rays diffracted through an angle of 62°. If the wavelength of the x-rays is 0.154 nm what is the inter-planar spacing of the diffracting planes? From Bragg’s law: θ λ sin 2 n d = Note however that the angle marked on the diagram is 2 θ , not θ , i.e. θ = 31°. Thus, letting n = 1, nm x d 1495 . 0 515 . 0 2 154 . 0 31
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Mid Term Test 2002 Solutions - Engin Mater 2O03 Mid-Term...

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