Added(A)/Deleted(D) following books

 M  hfgd_by_Gayakwad/README.txt
A  hfgd_by_Gayakwad/ami.ipynb
A  hfgd_by_Gayakwad/screenshots/amit_Das.png
A  hfgd_by_Gayakwad/screenshots/anshul_gvBijDQ.png
A  hfgd_by_Gayakwad/screenshots/array_factor.png
A  "sample_notebooks/Nitin Kumar/chapter2.ipynb"
A  "sample_notebooks/amit kumarsaini/Chapter4.ipynb"

7 files changed, 1148 insertions, 8 deletions

diff --git a/hfgd_by_Gayakwad/README.txt b/hfgd_by_Gayakwad/README.txt
index 55aba71c..c20c3d73 100755
--- a/hfgd_by_Gayakwad/README.txt
+++ b/hfgd_by_Gayakwad/README.txt
@@ -1,10 +1,10 @@
-Contributed By: Jeevan Lal
-Course: me
-College/Institute/Organization: MPBtech. ECE, 6th SemVNIT Nagpur
-Department/Designation: MPBtech. ECE, 6th SemVNIT Nagpur
+Contributed By: Kushal R
+Course: mscit
+College/Institute/Organization: -
+Department/Designation: -
 Book Title: hfgd
 Author: Gayakwad
-Publisher: sdf
-Year of publication: 2001
-Isbn: 444
-Edition: 9
\ No newline at end of file
+Publisher: e
+Year of publication: 3
+Isbn: 67
+Edition: r
\ No newline at end of file
diff --git a/hfgd_by_Gayakwad/ami.ipynb b/hfgd_by_Gayakwad/ami.ipynb
new file mode 100644
index 00000000..c1ea8d5d
--- /dev/null
+++ b/hfgd_by_Gayakwad/ami.ipynb
@@ -0,0 +1,230 @@
+{

+ "metadata": {

+  "name": "",

+  "signature": "sha256:52168f8cf69a70c4ff180e7d64c2bf193739db268ee5cdc6db9f3696c7774225"

+ },

+ "nbformat": 3,

+ "nbformat_minor": 0,

+ "worksheets": [

+  {

+   "cells": [

+    {

+     "cell_type": "heading",

+     "level": 1,

+     "metadata": {},

+     "source": [

+      "Chapter4-Basic Terms of Physics and Engineering"

+     ]

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex1-pg61"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#find the area piston for given parameters\n",

+      "#given\n",

+      "a=3.\n",

+      "#diameter squared\n",

+      "#calculation\n",

+      "A=0.785*3**2\n",

+      "print\"%s %.2f %s\"%(\"area of piston \",A,\"\")\n"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "area of piston  7.07 \n"

+       ]

+      }

+     ],

+     "prompt_number": 1

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex2-pg62"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#find the area of piston and displacement of that piston\n",

+      "a=3.\n",

+      "b=4.\n",

+      "A=0.785*3**2\n",

+      "print\"%s %.2f %s\"%(\"area of piston \",A,\"\")\n",

+      "D=A*b\n",

+      "#by using above results\n",

+      "print\"%s %.2f %s\"%(\"displacement of piston \",D,\"cu in\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "area of piston  7.07 \n",

+        "displacement of piston  28.26 cu in\n"

+       ]

+      }

+     ],

+     "prompt_number": 2

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex3-pg63"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#find the piston speed\n",

+      "pa=9.\n",

+      "S=1600.\n",

+      "#average piston velocity =distance traveld/time to travel\n",

+      "#first divide by 1 min and u will get same result late divide by 12 because to express per minute\n",

+      "Ps=(pa*S)/(12.)\n",

+      "print\"%s %.2f %s\"%(\"piston speed \",Ps,\"ft per min\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "piston speed  1200.00 ft per min\n"

+       ]

+      }

+     ],

+     "prompt_number": 3

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex4-pg65"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#compute the average acceleration  `\n",

+      "#pressure= force/area\n",

+      "#first express the velocity in ft per sec.time\n",

+      "t=5.\n",

+      "v=9000.\n",

+      "Min=(9000./60.)\n",

+      "Aa=(Min/t)\n",

+      "print\"%s %.2f %s\"%(\"average acceleration\",Aa,\"ft per sec^2\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "average acceleration 30.00 ft per sec^2\n"

+       ]

+      }

+     ],

+     "prompt_number": 4

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex5-pg65"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#compute the pressure force\n",

+      "#given\n",

+      "w=12000.\n",

+      "p=6.\n",

+      "a=10**2\n",

+      "f=p*a\n",

+      "P=w/f\n",

+      "print\"%s %.2f %s\"%(\"pressure  \",P,\"Psi\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "pressure   20.00 Psi\n"

+       ]

+      }

+     ],

+     "prompt_number": 5

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex6-pg66"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#compute the gas force action on pistion \n",

+      "#use the figure to compute it \n",

+      "p=500.\n",

+      "D=5**2\n",

+      "#force=pressure*area\n",

+      "area=0.785*D\n",

+      "F=p*area\n",

+      "print\"%s %.2f %s\"%(\"force \",F,\"lb\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "force  9812.50 lb\n"

+       ]

+      }

+     ],

+     "prompt_number": 6

+    }

+   ],

+   "metadata": {}

+  }

+ ]

+}
\ No newline at end of file
diff --git a/hfgd_by_Gayakwad/screenshots/amit_Das.png b/hfgd_by_Gayakwad/screenshots/amit_Das.png
new file mode 100644
index 00000000..1789360b
--- /dev/null
+++ b/hfgd_by_Gayakwad/screenshots/amit_Das.png
diff --git a/hfgd_by_Gayakwad/screenshots/anshul_gvBijDQ.png b/hfgd_by_Gayakwad/screenshots/anshul_gvBijDQ.png
new file mode 100644
index 00000000..a8cec645
--- /dev/null
+++ b/hfgd_by_Gayakwad/screenshots/anshul_gvBijDQ.png
diff --git a/hfgd_by_Gayakwad/screenshots/array_factor.png b/hfgd_by_Gayakwad/screenshots/array_factor.png
new file mode 100644
index 00000000..9e294010
--- /dev/null
+++ b/hfgd_by_Gayakwad/screenshots/array_factor.png
diff --git a/sample_notebooks/Nitin Kumar/chapter2.ipynb b/sample_notebooks/Nitin Kumar/chapter2.ipynb
new file mode 100644
index 00000000..ddf5a2a5
--- /dev/null
+++ b/sample_notebooks/Nitin Kumar/chapter2.ipynb
@@ -0,0 +1,680 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter 2 - Power Switching Devices & Their Characteristics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.1 page 67"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "VA = 1.10 V\n"
+     ]
+    }
+   ],
+   "source": [
+    "V1=1    # V across SCR\n",
+    "IG=0    # A\n",
+    "Ih=2    # mA holding current\n",
+    "R=50    # ohm\n",
+    "\n",
+    "# Applying kirchoff law\n",
+    "#VA-(IAK*R)-V1=0\n",
+    "VA=(Ih*10**-3*R)+V1    # V (let IAK=Ih)\n",
+    "print 'VA = %.2f V'%(VA)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.2 page 67"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Minimum duration of gating pulse = 10 us\n"
+     ]
+    }
+   ],
+   "source": [
+    "diBYdt=1000    # A/s (rate of rise of current)\n",
+    "il=10    # mA (latching current = diBYdt * tp)\n",
+    "tp=il*10**-3/diBYdt    # s\n",
+    "print 'Minimum duration of gating pulse = %.f us'%(tp*10**6)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.3 page 68"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Gate power dissipation = 4 W\n",
+      "\n",
+      " Resistance to be connected = 14 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "m=16    #  V/A (gradient)\n",
+    "t_on=4    #  us\n",
+    "IG=500    #  mA\n",
+    "VS=15    #  V\n",
+    "\n",
+    "VG=m*IG/1000    #  V\n",
+    "#Load line equation\n",
+    "#VG=VS-IG*RS\n",
+    "RS=(VS-VG)/(IG/1000)     #  ohm\n",
+    "Pg=VS*(IG/1000)**2 # # W\n",
+    "print 'Gate power dissipation = %.f W'%(Pg)\n",
+    "print '\\n Resistance to be connected = %.f ohm'%(RS)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.4 page 68"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Value of resistance to be added in series = 44.11 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from numpy import roots\n",
+    "# VG=0.5+8*IG -- eqn(1)\n",
+    "f=400# # Hz\n",
+    "delta=0.1 # # (Duty Cycle)\n",
+    "P=0.5    # W\n",
+    "VS=12    #  V\n",
+    "\n",
+    "Tp=1/f*10**6    #  us\n",
+    "# P= VG*IG -- eqn(2)\n",
+    "# solving eqn  1 and 2\n",
+    "#8*IG*IG**2+0.5*IG-P=0\n",
+    "p=[8, 0.5, -P] # polynomial for IG\n",
+    "IG=roots(p)     #  A \n",
+    "IG=IG[1]     #  A (discarding -ve value)\n",
+    "VG=0.5+8*IG    #  V\n",
+    "# VS=VG+IG*RS\n",
+    "RS=(VS-VG)/IG\n",
+    "print 'Value of resistance to be added in series = %.2f ohm'%(RS)\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.5 page 69"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Value of resistance to be connected in series = 6.97 ohm\n",
+      "\n",
+      " Triggering frequency = 5.00 kHz\n",
+      "\n",
+      " Duty Cycle = 0.1 \n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import sqrt\n",
+    "# VG=10*IG -- eqn(1)\n",
+    "PGM=5    #  W\n",
+    "PGav=.5    #  W\n",
+    "VS=12    #  V\n",
+    "Tp=20    #  us\n",
+    "\n",
+    "# PGM = VG*IG where VG=10*IG\n",
+    "\n",
+    "IG=sqrt(PGM/10)    #  A\n",
+    "VG=10*IG    #  V\n",
+    "# During the application of pulse VS = VG+(IG*RS)\n",
+    "RS=(VS-VG)/IG     #  ohm\n",
+    "f=PGav/(PGM*Tp*10**-6)/1000    #  kHz\n",
+    "delta=f*1000*Tp*10**-6    #  Duty Cycle\n",
+    "print 'Value of resistance to be connected in series = %.2f ohm'%(RS)\n",
+    "print '\\n Triggering frequency = %.2f kHz'%(f)\n",
+    "print '\\n Duty Cycle = %.1f '%(delta)\n",
+    "# Note : ans in the textbook is not accurate."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.6 page 70"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Value of R = 31.25 kohm\n",
+      "\n",
+      " Value of C = 1.20e-07 F\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "VS=3    #  kV\n",
+    "IS=750    #  A\n",
+    "\n",
+    "VD=800    #  V\n",
+    "ID=175    #  A\n",
+    "dr=30/100    #  de-rating factor\n",
+    "IB=8    # mA\n",
+    "delQ=30    #  u Coulomb\n",
+    "# dr = 1-IS/np*ID\n",
+    "np = round(IS/(1-dr)/(ID)) # # no. of parallel string\n",
+    "ns = round(VS*1000/(1-dr)/(VD)) # # no. of series string\n",
+    "R=(ns*VD-VS*1000)/(ns-1)/(IB/1000)/1000    # kohm\n",
+    "C=(ns-1)*delQ*10**-6/(ns*VD-VS*1000)\n",
+    "print 'Value of R = %.2f kohm'%(R)\n",
+    "print '\\n Value of C = %.2e F'%(C)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.7 page 71"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " no. of series connection = 7\n",
+      "\n",
+      " no. of parallel connection = 5\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import ceil\n",
+    "VS=4    #  kV\n",
+    "IS=800    #  A\n",
+    "\n",
+    "VD=800    #  V\n",
+    "ID=200    #  A\n",
+    "dr=20/100    #  de-rating factor\n",
+    "# for series connection\n",
+    "ns = ceil(VS*1000/(1-dr)/(VD)) # # no. of series string\n",
+    "# for parallel connection\n",
+    "np = round(IS/(1-dr)/(ID)) # # no. of parallel string\n",
+    "print '\\n no. of series connection = %d'%(ns)\n",
+    "print '\\n no. of parallel connection = %d'%(np)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.8 page 72"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      " Series resistance = 0.007 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "IS1=100    #  A\n",
+    "IS2=150    #  A\n",
+    "vd1=2.1    #  V\n",
+    "vd2=1.75    #  V\n",
+    "I=250    #  A\n",
+    "\n",
+    "rf1=vd1/IS1    #  ohm\n",
+    "rf2=vd2/IS2    #  ohm\n",
+    "# Equating voltage drops\n",
+    "# vd1+IS1*re = vd2+IS2*re\n",
+    "re=(vd1-vd2)/(IS2-IS1)\n",
+    "print ' Series resistance = %.3f ohm'%(re)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.9 page 72"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Average power loss = 34.8 W\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi\n",
+    "Vf1=1    #  V\n",
+    "If1=0    # A\n",
+    "Vf2=1.9    #  V\n",
+    "If2=60    # A\n",
+    "IT=20*pi    #  A\n",
+    "# PAV = 1/T*integrate(VT*IT,0,T)*dt = ITAV+0.015*IRMS**2\n",
+    "ITAV=IT/pi    # A\n",
+    "ITRMS=IT/2    #  A\n",
+    "dt=ITAV+0.015*ITRMS**2    #  W\n",
+    "print 'Average power loss = %.1f W'%(dt)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.10 page 73"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Minimum gate pulse width = 8.7 us\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "R=10    #  ohm\n",
+    "L=0.1    #  H\n",
+    "delta_i=20/1000    #  A\n",
+    "Vs=230    #  V4\n",
+    "f=50    #  Hz\n",
+    "theta=45    # degree\n",
+    "\n",
+    "delta_t = L*delta_i/Vs# # s\n",
+    "delta_t = delta_t*10**6    #  us\n",
+    "print 'Minimum gate pulse width = %.1f us'%(delta_t)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.11 page 73"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "gate source resistance = 2.0 kohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import sqrt\n",
+    "m=3*10**3    #  gradient (VG/IG)\n",
+    "VS=10    #  V\n",
+    "PG=0.012    #  W\n",
+    "# IG = VG/m & PG=VG*IG\n",
+    "VG=sqrt(PG*m)\n",
+    "IG=VG/m # # A\n",
+    "RS=(VS-VG)/IG/1000    #  kohm\n",
+    "print 'gate source resistance = %.1f kohm'%(RS)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.12 page 74"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Value of resistance = 6.82 kohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "VS=300    #  V\n",
+    "delta_i = 50/1000    #  A\n",
+    "R=60    #  ohm\n",
+    "L=2    #  H\n",
+    "TP=40*10**-6    #  s\n",
+    "\n",
+    "I1=VS/L*TP    #  A (at the end of pulse)\n",
+    "# as I1 << delta_i\n",
+    "I2=delta_i    #  A (anode current with RL load)\n",
+    "\n",
+    "Rdash = VS/(I2-I1)/1000    #  kohm\n",
+    "print 'Value of resistance = %.2f kohm'%(Rdash)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.13 page 74"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "For half sine wave current : \n",
+      "\n",
+      "(i) Average ON State current  = 31.83 A\n",
+      "\n",
+      "(ii) Average ON State current  = 22.51 A\n",
+      "\n",
+      "(iii) Average ON State current  = 12.54 A\n",
+      "\n",
+      "\n",
+      " For rectangular wave current : \n",
+      "\n",
+      "(i) Average ON State current  = 35.36 A\n",
+      "\n",
+      "(ii) Average ON State current  = 25.00 A\n",
+      "\n",
+      "(i) Average ON State current  = 14.43 A\n",
+      "\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi,sqrt\n",
+    "Im=50    #  A\n",
+    "\n",
+    "print 'For half sine wave current : \\n'\n",
+    "# theta=180    #  degree\n",
+    "theta=180    #  degree\n",
+    "Iav=Im/pi    #  A\n",
+    "Irms=Im/2    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(i) Average ON State current  = %.2f A\\n'%(ITav)    \n",
+    "\n",
+    "# theta=90    #  degree\n",
+    "theta=90    #  degree\n",
+    "Iav=Im/2/pi    #  A\n",
+    "Irms=Im/2/sqrt(2)    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(ii) Average ON State current  = %.2f A\\n'%(ITav)    \n",
+    "\n",
+    "# theta=180    #  degree\n",
+    "theta=180    #  degree\n",
+    "Iav=Im*0.0213    #  A\n",
+    "Irms=Im*0.0849    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(iii) Average ON State current  = %.2f A\\n'%(ITav)    \n",
+    "\n",
+    "print '\\n For rectangular wave current : \\n'\n",
+    "# theta=180    #  degree\n",
+    "theta=180    #  degree\n",
+    "Iav=Im/2    #  A\n",
+    "Irms=Im/sqrt(2)    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(i) Average ON State current  = %.2f A\\n'%(ITav)    \n",
+    "\n",
+    "# theta=90    #  degree\n",
+    "theta=90    #  degree\n",
+    "Iav=Im/4    #  A\n",
+    "Irms=Im/2    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(ii) Average ON State current  = %.2f A\\n'%(ITav)    \n",
+    "\n",
+    "# theta=180    #  degree\n",
+    "theta=180    #  degree\n",
+    "Iav=Im/12    #  A\n",
+    "Irms=Im/2/sqrt(3)    #  A\n",
+    "FF=Irms/Iav    #  form factor\n",
+    "ITav=Im/FF # # A\n",
+    "print '(i) Average ON State current  = %.2f A\\n'%(ITav)    "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.14 page 76"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Value of L = 16.67 uH\n",
+      "\n",
+      " Value of R = 3.3 ohm\n",
+      "\n",
+      " Value of Ip = 175.0 A is greater than permissible peak current = 125.0 A\n",
+      " change the value of Rs\n",
+      "\n",
+      " Value of C = 0.78 uF\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "VS=500    #  V\n",
+    "IP=250    #  A\n",
+    "diBYdt=60    #  A/us\n",
+    "dvaBYdt=200    #  V/us\n",
+    "RL=20    #  ohm\n",
+    "r=0.65    #  ohm\n",
+    "eps=0.65     #  damping ratios\n",
+    "\n",
+    "F=2    #  saftety factor\n",
+    "IP=IP/2    #  A\n",
+    "diBYdt=60/2    #  A/us\n",
+    "dvaBYdt=200/2    #  V/us\n",
+    "L=VS/diBYdt    #  uH\n",
+    "R=L*10**6/VS*dvaBYdt/10**6    #  ohm\n",
+    "print 'Value of L = %.2f uH'%(L)\n",
+    "print '\\n Value of R = %.1f ohm'%(R)\n",
+    "\n",
+    "Ip=VS/RL+VS/R    #  A\n",
+    "if Ip > IP :\n",
+    "    print '\\n Value of Ip = %.1f A is greater than permissible peak current = %.1f A\\n change the value of Rs'%(Ip,IP)\n",
+    "    Rs=6    # ohm\n",
+    "\n",
+    "Ip=VS/RL+VS/Rs    #  A\n",
+    "Cs=(2*eps/Rs)**2*L    #  uF\n",
+    "print '\\n Value of C = %.2f uF'%(Cs)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Ex 2.15 page 77"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "I2t rating = 45000 A**2/s\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import ceil,sqrt\n",
+    "Isb=3000    #  A\n",
+    "f=50    #  Hz\n",
+    "I=sqrt((Isb**2*1/2/f)*f)     #  A\n",
+    "I2t=I**2/2/f    #  A**2/s\n",
+    "print 'I2t rating = %d A**2/s'%(ceil(I2t))"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.9"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/sample_notebooks/amit kumarsaini/Chapter4.ipynb b/sample_notebooks/amit kumarsaini/Chapter4.ipynb
new file mode 100644
index 00000000..c1ea8d5d
--- /dev/null
+++ b/sample_notebooks/amit kumarsaini/Chapter4.ipynb
@@ -0,0 +1,230 @@
+{

+ "metadata": {

+  "name": "",

+  "signature": "sha256:52168f8cf69a70c4ff180e7d64c2bf193739db268ee5cdc6db9f3696c7774225"

+ },

+ "nbformat": 3,

+ "nbformat_minor": 0,

+ "worksheets": [

+  {

+   "cells": [

+    {

+     "cell_type": "heading",

+     "level": 1,

+     "metadata": {},

+     "source": [

+      "Chapter4-Basic Terms of Physics and Engineering"

+     ]

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex1-pg61"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#find the area piston for given parameters\n",

+      "#given\n",

+      "a=3.\n",

+      "#diameter squared\n",

+      "#calculation\n",

+      "A=0.785*3**2\n",

+      "print\"%s %.2f %s\"%(\"area of piston \",A,\"\")\n"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "area of piston  7.07 \n"

+       ]

+      }

+     ],

+     "prompt_number": 1

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex2-pg62"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#find the area of piston and displacement of that piston\n",

+      "a=3.\n",

+      "b=4.\n",

+      "A=0.785*3**2\n",

+      "print\"%s %.2f %s\"%(\"area of piston \",A,\"\")\n",

+      "D=A*b\n",

+      "#by using above results\n",

+      "print\"%s %.2f %s\"%(\"displacement of piston \",D,\"cu in\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "area of piston  7.07 \n",

+        "displacement of piston  28.26 cu in\n"

+       ]

+      }

+     ],

+     "prompt_number": 2

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex3-pg63"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#find the piston speed\n",

+      "pa=9.\n",

+      "S=1600.\n",

+      "#average piston velocity =distance traveld/time to travel\n",

+      "#first divide by 1 min and u will get same result late divide by 12 because to express per minute\n",

+      "Ps=(pa*S)/(12.)\n",

+      "print\"%s %.2f %s\"%(\"piston speed \",Ps,\"ft per min\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "piston speed  1200.00 ft per min\n"

+       ]

+      }

+     ],

+     "prompt_number": 3

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex4-pg65"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#compute the average acceleration  `\n",

+      "#pressure= force/area\n",

+      "#first express the velocity in ft per sec.time\n",

+      "t=5.\n",

+      "v=9000.\n",

+      "Min=(9000./60.)\n",

+      "Aa=(Min/t)\n",

+      "print\"%s %.2f %s\"%(\"average acceleration\",Aa,\"ft per sec^2\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "average acceleration 30.00 ft per sec^2\n"

+       ]

+      }

+     ],

+     "prompt_number": 4

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex5-pg65"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#compute the pressure force\n",

+      "#given\n",

+      "w=12000.\n",

+      "p=6.\n",

+      "a=10**2\n",

+      "f=p*a\n",

+      "P=w/f\n",

+      "print\"%s %.2f %s\"%(\"pressure  \",P,\"Psi\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "pressure   20.00 Psi\n"

+       ]

+      }

+     ],

+     "prompt_number": 5

+    },

+    {

+     "cell_type": "heading",

+     "level": 2,

+     "metadata": {},

+     "source": [

+      "Ex6-pg66"

+     ]

+    },

+    {

+     "cell_type": "code",

+     "collapsed": false,

+     "input": [

+      "#given\n",

+      "#compute the gas force action on pistion \n",

+      "#use the figure to compute it \n",

+      "p=500.\n",

+      "D=5**2\n",

+      "#force=pressure*area\n",

+      "area=0.785*D\n",

+      "F=p*area\n",

+      "print\"%s %.2f %s\"%(\"force \",F,\"lb\")"

+     ],

+     "language": "python",

+     "metadata": {},

+     "outputs": [

+      {

+       "output_type": "stream",

+       "stream": "stdout",

+       "text": [

+        "force  9812.50 lb\n"

+       ]

+      }

+     ],

+     "prompt_number": 6

+    }

+   ],

+   "metadata": {}

+  }

+ ]

+}
\ No newline at end of file