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   "source": [
    "# 10: Lasers"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example number 1, Page number 10-20"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "band gap is 0.8 eV\n"
     ]
    }
   ],
   "source": [
    "#importing modules\n",
    "import math\n",
    "from __future__ import division\n",
    "\n",
    "#Variable declaration\n",
    "c=3*10**8;                 #velocity of light(m/s)\n",
    "h=6.63*10**-34;            #plank's constant(Js)\n",
    "e=1.6*10**-19;             #charge(coulomb)\n",
    "lamda=1.55*10**-6;         #wavelength(m)\n",
    "\n",
    "#Calculation\n",
    "Eg=h*c/(lamda*e);          #band gap(eV)   \n",
    "\n",
    "#Result\n",
    "print \"band gap is\",round(Eg,1),\"eV\""
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example number 2, Page number 10-20"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "wavelength is 8633 angstrom\n"
     ]
    }
   ],
   "source": [
    "#importing modules\n",
    "import math\n",
    "from __future__ import division\n",
    "\n",
    "#Variable declaration\n",
    "c=3*10**8;                 #velocity of light(m/s)\n",
    "h=6.63*10**-34;            #plank's constant(Js)\n",
    "e=1.6*10**-19;             #charge(coulomb)\n",
    "Eg=1.44*e;                 #band gap(eV)   \n",
    "\n",
    "#Calculation\n",
    "lamda=h*c*10**10/Eg;       #wavelength(angstrom)\n",
    "\n",
    "#Result\n",
    "print \"wavelength is\",int(round(lamda)),\"angstrom\""
   ]
  }
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