{
"metadata": {
"name": "",
"signature": "sha256:4564535166c2472d72e2dcbe6fdb282dd0ebdfe6b75d04aed6f0238329c6aca1"
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"nbformat": 3,
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"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"5: Magnetostatics"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.1, Page number 118"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"m=1.7*10**-27; #mass of proton(kg)\n",
"q=1.6*10**-19; #charge of proton(C)\n",
"KE=6*10**6*q; #kinetic energy of proton(J) \n",
"B=2; #intensity of magnetic field(Wb/m**2)\n",
"theta=90*math.pi/180; #angle(radian)\n",
"\n",
"#Calculation\n",
"v=math.sqrt(2*KE/m); #velocity(m/s)\n",
"Fb=q*v*B*math.sin(theta); #force acting on proton(N)\n",
"\n",
"#Result\n",
"print \"force acting on proton is\",round(Fb*10**11,3),\"*10**-11 N\"\n",
"print \"answer given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"force acting on proton is 1.075 *10**-11 N\n",
"answer given in the book is wrong\n"
]
}
],
"prompt_number": 12
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.2, Page number 119"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"r=6.4*10**6; #radius of earth(m)\n",
"P=6.4*10**21; #magnetic moment(Amp m**2)\n",
"\n",
"#Calculation\n",
"A=math.pi*(r**2); #area(m**2)\n",
"i=P/A; #current(amp)\n",
"\n",
"#Result\n",
"print \"current is\",round(i/10**7),\"*10**7 Amp\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"current is 5.0 *10**7 Amp\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.3, Page number 119"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"B0=1.7*10**-5; #magnetic flux density(Wb/m**2)\n",
"mew0=4*math.pi*10**-7; \n",
"\n",
"#Calculation\n",
"H=B0/mew0; #magnetic intensity(Amp/m)\n",
"\n",
"#Result\n",
"print \"magnetic intensity is\",round(H,1),\"Amp/m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"magnetic intensity is 13.5 Amp/m\n"
]
}
],
"prompt_number": 14
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.4, Page number 119"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"l=30*10**-2; #length(m)\n",
"A=10**-4; #area(m**2)\n",
"N=300; #number of turns\n",
"i=0.032; #current(ampere)\n",
"phi=2*10**-6; #magnetic flux(Wb)\n",
"mew0=4*math.pi*10**-7; \n",
"\n",
"#Calculation\n",
"B=phi/A; #magnetic flux density(wb/m**2)\n",
"H=N*i/l; #magnetising force(amp turns/m)\n",
"mew=B/H; #permeability of ion(Wb/Amp m)\n",
"mewr=mew/mew0; #relative permeability\n",
"\n",
"#Result\n",
"print \"magnetic flux density is\",B*10**2,\"*10**-2 wb/m**2\"\n",
"print \"magnetising force is\",H,\"amp turns/m\"\n",
"print \"permeability of ion is\",mew*10**4,\"*10**-4 Wb/Amp m\"\n",
"print \"relative permeability is\",round(mewr)\n",
"print \"answer for relative permeability differs due to round off errors\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"magnetic flux density is 2.0 *10**-2 wb/m**2\n",
"magnetising force is 32.0 amp turns/m\n",
"permeability of ion is 6.25 *10**-4 Wb/Amp m\n",
"relative permeability is 497.0\n",
"answer for relative permeability differs due to round off errors\n"
]
}
],
"prompt_number": 20
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.5, Page number 120"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"M=600; #magnetic moment(cgs units)\n",
"V=20; #volume(cm**3)\n",
"H=50; #magnetic field(oersteds)\n",
"\n",
"#Calculation\n",
"I=M/V; #intensity of magnetisation(cgs units)\n",
"B=H+(4*math.pi*I); #flux density(guass)\n",
"\n",
"#Result\n",
"print \"flux density is\",round(B),\"guass\"\n",
"print \"answer given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"flux density is 427.0 guass\n",
"answer given in the book is wrong\n"
]
}
],
"prompt_number": 23
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.6, Page number 120"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"m=12000; #mass(gm)\n",
"d=7.5; #density(g/cm**3)\n",
"new=50; #frequency(Hz)\n",
"a=3000; #area of hysterisis curve(erg/cm**3)\n",
"\n",
"#Calculation\n",
"V=m/d; #volume of core(cm**3)\n",
"El=a*V; #energy loss in 1 cycle(erg)\n",
"n=new*60*60; #number of cycles per hour\n",
"EL=El*n/10**7; #energy loss per hour(J)\n",
"\n",
"#Result\n",
"print \"energy loss per hour is\",EL/10**4,\"*10**4 J\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"energy loss per hour is 8.64 *10**4 J\n"
]
}
],
"prompt_number": 24
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.7, Page number 121"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"B=8*math.pi; #magnetic flux density(wb/m**2)\n",
"H=2000; #magnetic field(amp turn/m)\n",
"mew0=4*math.pi*10**-7; \n",
"\n",
"#Calculation\n",
"mewr=B/(mew0*H); #relative permeability\n",
"chi=mewr-1; #susceptibility\n",
"\n",
"#Result\n",
"print \"susceptibility is\",chi"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"susceptibility is 9999.0\n"
]
}
],
"prompt_number": 25
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.8, Page number 121"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"q=1.6*10**-19; #charge on electron(C)\n",
"i1=3;\n",
"j1=2;\n",
"k1=3; #components of vector\n",
"i2=3;\n",
"j2=4; \n",
"k2=0; #components of vector\n",
"i3=0;\n",
"j3=4;\n",
"k3=1; #components of vector\n",
"\n",
"#Calculation\n",
"i4=(j2*k3)-(j3*k2);\n",
"j4=(i2*k3)-(i3*k2);\n",
"k4=(i2*j3)-(i3*j2); #components of derived vector\n",
"i5=i1+i4;\n",
"j5=j1+j4;\n",
"k5=k1+k4;\n",
"F=q*math.sqrt((i5**2)+(j5**2)+(k5**2)); #Lorentz force(N)\n",
"\n",
"#Result\n",
"print \"Lorentz force is\",round(F*10**19,2),\"*10**-19 N\"\n",
"print \"answer given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Lorentz force is 27.67 *10**-19 N\n",
"answer given in the book is wrong\n"
]
}
],
"prompt_number": 29
}
],
"metadata": {}
}
]
}