The Miller indices of a material in a plane are proportional to

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ESE Mechanical 2016 Paper 2: Official Paper
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  1. The reciprocal of numerical parameters of the intercepts
  2. The square of unit cell dimensions
  3. The intercepts of the planes on the coordinate axes
  4. The interplanar spacing

Answer (Detailed Solution Below)

Option 1 : The reciprocal of numerical parameters of the intercepts
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Detailed Solution

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Concept:

Miller indices are the styles to designate the planes and directions in the unit cells and crystals.

Miller indices (hkl) are expressed as a reciprocal of intercepts p, q, and r made by the plane on the three rectangular axes x, y and z respectively. These are the unit distances from the origin along the three axes. Thus

\(h=\frac{1}{p},~k=\frac{1}{q},~l=\frac{1}{r}\)

where, p = intercept of the plane on the x-axis, q = intercept of the plane on the y-axis, and r = intercept of the plane on the z-axis.

Reciprocal of these intercepts are then converted into whole numbers. This can be done by multiplying each reciprocal by a number obtained after taking LCM of the denominator.

This gives the Miller indices of the required plane. The Miller indices are expressed by three smallest integers. 

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