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   "source": [
    "# Chapter 15 : Alternating voltage & current"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_1 Page No: 546"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Voltage at 30° = 50.00 Volts\n",
      "The Voltage at 45° = 70.71 Volts\n",
      "The Voltage at 90° = 100.00 Volts\n",
      "The Voltage at 270° = -100.00 Volts\n"
     ]
    }
   ],
   "source": [
    "from numpy import sin, pi\n",
    "# A sine wave of voltage varies from zero to a maximum of 100 V. How much is the voltage at the instant of 30° of the cycle? 45°? 90°? 270°?\n",
    "\n",
    "# Given data\n",
    "\n",
    "Vm = 100#       # Vm=100 Volts\n",
    "t1 = 30#        # Theta 1=30°.\n",
    "t2 = 45#        # Theta 2=45°.\n",
    "t3 = 90#        # Theta 3=90°.\n",
    "t4 = 270#       # Theta 4=270°.\n",
    "\n",
    "v1 = Vm*sin(t1*pi/180)\n",
    "print 'The Voltage at 30° = %0.2f Volts'%v1\n",
    "\n",
    "v2 = Vm*sin(t2*pi/180)\n",
    "print 'The Voltage at 45° = %0.2f Volts'%v2\n",
    "\n",
    "v3 = Vm*sin(t3*pi/180)\n",
    "print 'The Voltage at 90° = %0.2f Volts'%v3\n",
    "\n",
    "v4 = Vm*sin(t4*pi/180)\n",
    "print 'The Voltage at 270° = %0.2f Volts'%v4"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_2 Page No: 548"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Time period = 1e-03 Seconds\n",
      "i.e 1/1000 sec\n",
      "The Frequency = 1000.00 Hertz\n",
      "OR 1 kHz\n"
     ]
    }
   ],
   "source": [
    "from __future__ import division\n",
    "# An alternating current varies through one complete cycle in 1 ⁄ 1000 s. Calculate the period and frequency.\n",
    "\n",
    "# Given data\n",
    "\n",
    "tc = 1/1000#        # One Complete Cycle=1 ⁄ 1000 sec.\n",
    "\n",
    "T = tc#\n",
    "print 'The Time period = %0.e Seconds'%T\n",
    "print 'i.e 1/1000 sec'\n",
    "\n",
    "f = 1/tc#\n",
    "print 'The Frequency = %0.2f Hertz'%f\n",
    "print 'OR 1 kHz'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_3 Page No: 549"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Time period = 1e-06 Seconds of 1 MHz freq.\n",
      "i.e 1*10**-6 sec = 1 usec\n",
      "The Time period = 5e-07 Seconds of 2 MHz freq.\n",
      "i.e 0.5*10**-6 sec = 0.5 usec\n"
     ]
    }
   ],
   "source": [
    "# Calculate the period for the two frequencies of 1 MHz and 2 MHz.Calculate the period for the two frequencies of 1 MHz and 2 MHz.\n",
    "\n",
    "# Given data\n",
    "\n",
    "f1 = 1*10**6#        # Freq=1 MHz\n",
    "f2 = 2*10**6#        # Freq=2 MHz\n",
    "\n",
    "t1 = 1/f1#\n",
    "print 'The Time period = %0.e Seconds of 1 MHz freq.'%t1\n",
    "print 'i.e 1*10**-6 sec = 1 usec'\n",
    "\n",
    "t2 = 1/f2#\n",
    "print 'The Time period = %0.e Seconds of 2 MHz freq.'%t2\n",
    "print 'i.e 0.5*10**-6 sec = 0.5 usec'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_4 Page No: 549"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Lamda or Wavelenght = 1.00 cm\n"
     ]
    }
   ],
   "source": [
    "# Calculate lamda for a radio wave witf f of 30 GHz.\n",
    "\n",
    "# Given data\n",
    "\n",
    "c = 3*10**10#     # Speed of light=3*10**10 cm/s\n",
    "f = 30*10**9#        # Freq=30 GHz\n",
    "\n",
    "l = c/f#\n",
    "print 'The Lamda or Wavelenght = %0.2f cm'%l"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_5 Page No: 550"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Height = 250.00 cm\n",
      "The Height = 8.20 feet\n"
     ]
    }
   ],
   "source": [
    "# The length of a TV antenna is lamda\u0005/2 for radio waves with f of 60 MHz. What is the antenna length in centimeters and feet?\n",
    "\n",
    "# Given data\n",
    "\n",
    "c = 3*10**10#     # Speed of light=3*10**10 cm/s\n",
    "f = 60*10**6#     # Freq=60 MHz\n",
    "In = 2.54#       # 2.54 cm = 1 in\n",
    "ft = 12#         # 12 in = 1 ft\n",
    "\n",
    "l1 = c/f#\n",
    "l = l1/2#\n",
    "print 'The Height = %0.2f cm'%l\n",
    "\n",
    "li = l/In\n",
    "lf = li/ft#\n",
    "print 'The Height = %0.2f feet'%lf"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_6 Page No: 550"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Frequency = 50000000 Hertz\n",
      "i.e 50*10**6 Hz OR 50 MHz\n"
     ]
    }
   ],
   "source": [
    "# For the 6-m band used in amateur radio, what is the corresponding frequency?\n",
    "\n",
    "# Given data\n",
    "\n",
    "v = 3*10**10#     # Speed of light=3*10**10 cm/s\n",
    "l = 6*10**2#      # lamda=6 meter\n",
    "\n",
    "f = v/l\n",
    "print 'The Frequency = %0.f Hertz'%f\n",
    "print 'i.e 50*10**6 Hz OR 50 MHz'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_7 Page No: 551"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Lamda or Wavelenght = 11.30 ft\n"
     ]
    }
   ],
   "source": [
    "# What is the wavelength of the sound waves produced by a loudspeaker at a frequency of 100 Hz?\n",
    "\n",
    "# Given data\n",
    "\n",
    "c = 1130#   # Speed of light=1130 ft/s\n",
    "f = 100#    # Freq=100 Hz\n",
    "\n",
    "l = c/f#\n",
    "print 'The Lamda or Wavelenght = %0.2f ft'%l"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example No. 15_8 Page No: 552"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "The Lamda or Wavelength = 0.03 ft\n",
      "The Lamda or Wavelength = 1.00 cm\n"
     ]
    }
   ],
   "source": [
    "# For ultrasonic waves at a frequency of 34.44 kHz, calculate the wavelength in feet and in centimeters.\n",
    "\n",
    "# Given data\n",
    "\n",
    "c = 1130#   # Speed of light=1130 ft/s\n",
    "f = 34.44*10**3#    # Freq=100 Hz\n",
    "In = 2.54#       # 2.54 cm = 1 in\n",
    "ft = 12#         # 12 in = 1 ft\n",
    "\n",
    "l = c/f#\n",
    "print 'The Lamda or Wavelength = %0.2f ft'%l\n",
    "\n",
    "a = l*ft#\n",
    "\n",
    "l1 = a*In#\n",
    "print 'The Lamda or Wavelength = %0.2f cm'%l1"
   ]
  }
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