{
 "cells": [
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   "source": [
    "# Chapter22 Crystals"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example 22.1, Page no.81"
   ]
  },
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   "execution_count": 1,
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     "text": [
      "distance between planes = 50.0 M A\n",
      "distance between planes = 70.71 M A\n",
      "distance between planes = 28.87 M A\n"
     ]
    }
   ],
   "source": [
    "import math\n",
    "#initialisation of variables\n",
    "from math import sqrt\n",
    "d=0.856 #g/ cc\n",
    "N=6*10**23 # molecules\n",
    "M=39.1 #g moleˆ−1\n",
    "n=2\n",
    "n1=4\n",
    "n2=12\n",
    "#CALCULATIONS \n",
    "a=(n*M/(N*d))**(1/3) \n",
    "d=a*10**8/ sqrt(n1)\n",
    "d1=a*10**8/ sqrt(n) \n",
    "d2=a*10**8/ sqrt(n2) \n",
    "#RESULTS\n",
    "d=d/10**6\n",
    "d1=d1/10**6\n",
    "d2=d2/10**6\n",
    "d1=round(d1,2)\n",
    "d2=round(d2,2)\n",
    "print 'distance between planes =',d,'M A'\n",
    "print 'distance between planes =',d1,'M A'\n",
    "print 'distance between planes =',d2,'M A'"
   ]
  }
 ],
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