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(CENG151)[2005](f)midterm~jcychan^sol_10029.pdf
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Quiz #1 of CENG 151
Introduction to Materials Science and Engineering
September 29, 2005 (Thursday)
LTG 12:00 - 1:20 pm
Name:
Student ID Department
1.
Please name the following planes.When you are to move the origin, please indicate where the origin is. (10 points)


2.
Please group the plane family. (10 points)














3.
Please name the following directions. (10 points)





4.
The following graph is the spectrum of x-ray diffraction for a FCC aluminium crystal, please answer the following: (30 points)


.
Why 111 is the strongest peak.


.
Please read the Figure caption and answer why it specifies that the sample needs to be in the powder form?


.
Can we just use one big piece of the aluminium single crystal to do the x-ray diffraction? What kind of diffraction pattern we would get if we used single crystal rather than the powdered sample?


.
For Figure 1, can we use the diffraction angle, , as the experimental variables instead of 2?






Figure 1 Diffraction pattern of aluminium powder. Each peak (in the plot of x-ray intensity versus diffraction angle, 2) represents diffraction of the x-ray beam by a set of parallel crystal planes (hkl) in various powder particles.

5.
Referring to the last question, if the x-ray diffraction is carried out for a crystal which has the simple cubic packing pattern, do you think that the strongest diffraction peak will be 111? Please give enough reasons and support your argument with detailed analysis. (25 points)


6.
Please derive the Braggs law using the Figure attached. (15 points)







Figure 2 Geometry for diffraction of x-radiation. The crystal structure is a three-dimensional diffraction grating. Bragg's law (n= 2d sin ) describes the diffraction condition.