Derivation of energy stored in an inductor

Please find the deductions as follows:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/Maths/Inductoren1.jpg


圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/Maths/Inductoren2.jpg

method 1
Energy story in an inductor = ∫ p dt
= ∫ i(L)(di/dt)dt (由0積到i)
= L∫ i di
=L [ i^2/2] (由0到i)
=L [i^2/2]=1/2(L)(i^2)
method 2
use the graph to derive
the slope of the graph= inductance L
the physical meaning of the graph is the energy stored,
so the energy stored in an inductor = the area under the curve=[(NФ)i]/2
=1/2[(Li)i] (Li=NФ)
=1/2[L(i^2)]

如果係AL，用METHOD就得....因為考試局唔要求考生一定要用積分去derive

2007-03-12 14:19:52 補充：
method 1Energy story in an inductor = ∫ p dt= ∫ i(L)(di/dt)dt (由0積到i) (energy=power x time)= L∫ i di=L [ i^2/2] (由0到i)=L [i^2/2]=1/2(L)(i^2)如果係AL，用METHOD2就得