path: root/Engineering_Physics_by_Rajendran/Chapter4.ipynb

{
 "metadata": {
  "name": "",
  "signature": "sha256:3f5941b661a8515cae38219efa7050e771c862dd351401d57b16c57806506e2a"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "4: Acoustics"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.1, Page number 24"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "I1=10**-12;   #intensity(W/m**2)\n",
      "I2=0.1;   #intensity of sound(W/m**2)\n",
      "\n",
      "#Calculation\n",
      "beta=10*np.log10(I2/I1);   #intensity level(dB) \n",
      "\n",
      "#Result\n",
      "print \"intensity level is\",beta,\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "intensity level is 110.0 dB\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.2, Page number 24"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "I1=10**-12;   #intensity(W/m**2)\n",
      "I2=10**-4;   #intensity of sound(W/m**2)\n",
      "\n",
      "#Calculation\n",
      "beta=10*np.log10(I2/I1);   #relative sound intensity(dB) \n",
      "\n",
      "#Result\n",
      "print \"relative sound intensity is\",beta,\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "relative sound intensity is 80.0 dB\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.3, Page number 25"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "I2byI1=2;    #intensity ratio\n",
      "\n",
      "#Calculation\n",
      "beta=10*np.log10(I2byI1);   #increase in sound intensity level(dB) \n",
      "\n",
      "#Result\n",
      "print \"increase in sound intensity level is\",round(beta,2),\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "increase in sound intensity level is 3.01 dB\n"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.4, Page number 25"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "P=3.14;   #power radiated(W)\n",
      "r=10;   #radius(m)\n",
      "I11=100;  #intensity(W/m**2)\n",
      "I12=1;   #intensity(W/m**2)\n",
      "I13=10**-12;  #intensity(W/m**2)\n",
      "\n",
      "#Calculation\n",
      "I2=P/(4*math.pi*r**2);   #intensity of sound(W/m**2)\n",
      "beta1=10*np.log10(I2/I11);   #relative intensity(dB) \n",
      "beta2=10*np.log10(I2/I12);   #relative intensity(dB) \n",
      "beta3=10*np.log10(I2/I13);   #relative intensity(dB) \n",
      "\n",
      "#Result\n",
      "print \"relative intensity with respect to 100W/m**2 is\",round(beta1,4),\"dB\"\n",
      "print \"relative intensity with respect to 1W/m**2 is\",round(beta2,4),\"dB\"\n",
      "print \"relative intensity with respect to 10**-12W/m**2 is\",round(beta3,3),\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "relative intensity with respect to 100W/m**2 is -46.0228 dB\n",
        "relative intensity with respect to 1W/m**2 is -26.0228 dB\n",
        "relative intensity with respect to 10**-12W/m**2 is 93.977 dB\n"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.5, Page number 26"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "P=1.5;   #power radiated(J/s)\n",
      "r=20;   #radius(m)\n",
      "I1=10**-12;  #intensity level of sound(W/m**2)\n",
      "\n",
      "#Calculation\n",
      "I2=P/(4*math.pi*r**2);   #intensity of sound(W/m**2)\n",
      "beta=10*np.log10(I2/I1);   #intensity level(dB) \n",
      "\n",
      "#Result\n",
      "print \"intensity level of sound is\",round(beta,1),\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "intensity level of sound is 84.7 dB\n"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.6, Page number 27"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "\n",
      "#Variable declaration\n",
      "beta1=80;   #intensity level of sound(dB)\n",
      "\n",
      "#Calculation\n",
      "\n",
      "\n",
      "#Result\n",
      "print \" \""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " \n"
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.7, Page number 28"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "\n",
      "#Variable declaration\n",
      "V=1500;   #volume of hall(m**3)\n",
      "sigma_a1s=100;   #absorption of sound by hall(sabine)\n",
      "sigma_a2s=100;   #absorption of sound by audience(sabine)\n",
      "\n",
      "#Calculation\n",
      "A=sigma_a1s+sigma_a2s;   #total absorption(sabine)\n",
      "t1=0.16*V/sigma_a1s;   #reverberation time of hall when room is empty(s)\n",
      "t2=0.16*V/(sigma_a1s+sigma_a2s);   #reverberation time of hall when room is filled(s)\n",
      "t=t1-t2;   #change in reverberation time(s)\n",
      "\n",
      "#Result\n",
      "print \"when the room is filled, reverberation time is reduced to\",t,\"s\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "when the room is filled, reverberation time is reduced to 1.2 s\n"
       ]
      }
     ],
     "prompt_number": 17
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.8, Page number 28"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "\n",
      "#Variable declaration\n",
      "V=1000;   #volume of hall(m**3)\n",
      "T=2;   #reverberation time(s)\n",
      "s=350;   #area of sound absorbing surface(m**2)\n",
      "\n",
      "#Calculation\n",
      "alpha=0.16*V/(T*s);   #average absorption coefficient\n",
      "\n",
      "#Result\n",
      "print \"average absorption coefficient is\",round(alpha,5)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "average absorption coefficient is 0.22857\n"
       ]
      }
     ],
     "prompt_number": 19
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.9, Page number 29"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "\n",
      "#Variable declaration\n",
      "V=2400;   #volume of hall(m**3)\n",
      "a1=500;   #area of plaster ceiling(m**2)\n",
      "s1=0.02;  #coefficient of absorption of plaster ceiling\n",
      "a2=600;   #area of plaster walls(m**2)\n",
      "s2=0.03;  #coefficient of absorption of plaster walls\n",
      "a3=500;   #area of wood floor(m**2)\n",
      "s3=0.06;  #coefficient of absorption of wood floor\n",
      "a4=20;    #area of wood doors(m**2)\n",
      "s4=0.06;  #coefficient of absorption of wood doors\n",
      "a5=400;   #area of cushion seats(m**2)\n",
      "s5=0.01;  #coefficient of absorption of cushion seats\n",
      "a6=200;   #area of cane seats(m**2)\n",
      "s6=0.01;  #coefficient of absorption of cane seats \n",
      "s=0.45;   #absorption of each member(sabine)\n",
      "\n",
      "#Calculation\n",
      "sigma_asE=(a1*s1)+(a2*s2)+(a3*s3)+(a4*s4)+(a5*s5)+(a6*s6);   #total absorption when hall is empty(sabine)\n",
      "TE=0.16*V/sigma_asE;   #reverberation time when hall is empty(s)\n",
      "sigma_asF=(a1*s1)+(a2*s2)+(a3*s3)+(a4*s4)+(a5*s)+(a6*s);    #total absorption when hall is filled(sabine)\n",
      "TF=0.16*V/sigma_asF;   #reverberation time when hall is filled(s)\n",
      "\n",
      "#Result\n",
      "print \"reverberation time when hall is empty is\",round(TE,4),\"s\"\n",
      "print \"reverberation time when hall is filled is\",round(TF,3),\"s\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "reverberation time when hall is empty is 5.8896 s\n",
        "reverberation time when hall is filled is 1.166 s\n"
       ]
      }
     ],
     "prompt_number": 23
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example number 4.10, Page number 30"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#importing modules\n",
      "import math\n",
      "from __future__ import division\n",
      "import numpy as np\n",
      "\n",
      "#Variable declaration\n",
      "I1=10**-12;   #intensity(W/m**2)\n",
      "I2=100;   #intensity of sound(W/m**2)\n",
      "\n",
      "#Calculation\n",
      "beta=10*np.log10(I2/I1);   #intensity level of jet plane(dB) \n",
      "\n",
      "#Result\n",
      "print \"intensity level of jet plane is\",beta,\"dB\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "intensity level of jet plane is 140.0 dB\n"
       ]
      }
     ],
     "prompt_number": 25
    }
   ],
   "metadata": {}
  }
 ]
}