electrical engineering

Electromagnetic Induction

<div dir="ltr" style="text-align: left;" trbidi="on"><div align="center"><span lang="EN-US" style="font-size: 20pt;"><span style="color: red;">Faraday’s Law of Electromagnetic Induction</span><br />
<span style="font-size: large;"><br />
</span> </span> </div><div align="center"><span lang="EN-US" style="font-size: large;">The magnitude of any induced e.m.f. (e) is proportional to the rate of change of magnetic flux linking the coil or circuit. This can be expressed mathematically as: </span></div><div align="center"><span style="font-size: large;">In words</span><span lang="EN-US" style="font-size: large;">, this equation says that the induced e.m.f. is equal to the rate at which magnetic flux is cut by the circuit or coil. </span></div><div class="O" v:shape="_x0000_s1026"><style>
.O
 {color:black;
 font-size:149%;}
a:link
 {color:#996600 !important;}
a:active
 {color:#3B812F !important;}
a:visited
 {color:#AFBF39 !important;}
</style><style media="print">

</style><span style="font-size: large;"><o:shapelayout style="color: blue;" v:ext="edit"></o:shapelayout><o:idmap data="1" style="color: blue;" v:ext="edit"></o:idmap><p:colorscheme colors="#ffffff,#000000,#5f5f5f,#006633,#cc9900,#3b812f,#996600,#afbf39" style="color: blue;"></p:colorscheme></span><br />
<div class="O" v:shape="_x0000_s1026"><div align="center" style="color: red; text-align: justify;"><nobr><br />
<span style="font-size: large;"><span style="color: red;"> Lenz’ Law</span></span><span lang="EN-US" style="color: red; font-size: large;"> </span></nobr></div><div style="text-align: justify;"><span lang="EN-US" style="font-size: large;"><br />
</span> <br />
<div align="center"><span lang="EN-US" style="font-size: large;">The direction of any induced e.m.f. will be so as to oppose the change that it is producing it. Hence the negative sign.</span><span lang="EN-US"><b><u> </u></b></span></div></div></div></div></div>

Electromagnetic Induction

Faraday’s Law of Electromagnetic Induction The magnitude of any induced e.m.f. (e) is proportional to the rate of change of magnetic flu...

more information

Magnetic Circuits

<div dir="ltr" style="text-align: left;" trbidi="on"><div style="color: blue;"><b><span style="font-size: large;">Ampere’s Circuital Law</span></b></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;">SI units</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;">Inet : is the net Ampere Turns (AT) enclosed within N-turns conductor.</span></div><div style="color: red;"><span style="font-size: large;">is the mean length of closed path (m</span></div><div style="color: red;"><span style="font-size: large;">H   : Field Intensity (AT/m). </span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: blue;"><b><span style="font-size: large;">Permeability</span></b></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;">FProperty that tell us how easily a magnetic</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;">field can flow through a material</span></div><div style="color: red;"><span style="font-size: large;">.</span></div><div style="color: red;"><span style="font-size: large;"> It is usually expressed in terms of relative permeability mr</span></div><div style="color: red;"><span style="font-size: large;"><br />
</span></div><div style="color: red;"><span style="font-size: large;"> The permeability is also the proportionality constant between an applied field intensity (H) and the resulting Magnetic Flux Density (B) :      B = mH   Þ    m = mo. mr  &  mo = 4p´10-7.</span></div></div>

Magnetic Circuits

Ampere’s Circuital Law SI units Inet : is the net Ampere Turns (AT) enclosed within N-turns conductor. is the mean length of closed path...

more information

Where Does the Magnetic Energy Come From

<div dir="ltr" style="text-align: left;" trbidi="on"><div style="color: red;"><span style="font-size: large;">A straight wire of length l is moved at right angles (with a velocity v) across a magnetic field of strength B. The wire will have an induced current I flowing through it and will thus experience a motor force on it given by     F = B × I × L</span></div><div style="color: red;"><span style="font-size: large;">Lenz’ Law states that the motor force will oppose the movement of the wire (i.e. the force will be in the opposite direction to the wire’s movement).</span></div><div style="color: red;"><span style="font-size: large;">The rate at which mechanical work is being done (i.e. power) against the motor force is given by    P = F × v = B × I × L × v </span></div><div style="color: red;"><span style="font-size: large;">We have previously derived an expression for the e.m.f. induced across such a straight wire:   F = B × L × v</span></div><div style="color: red;"><span style="font-size: large;">The electrical power generated in the wire is then the product of the e.m.f. and the induced current : P =  B × I × L × v = E × I</span></div></div>

Where Does the Magnetic Energy Come From

A straight wire of length l is moved at right angles (with a velocity v) across a magnetic field of strength B. The wire will have an induce...

more information