# Integral reason question

1. Aug 27, 2009

### nabliat

why they integrate in from 0 till I in order to find the energy on the inductor

http://i27.tinypic.com/11rfbyf.jpg

2. Aug 27, 2009

### rock.freak667

I'd think because as you turn on the circuit, the current through the conductor rises from 0 until it reaches the set current I, so the limits are from 0 to I.

3. Aug 27, 2009

### nabliat

look in this example
http://i28.tinypic.com/2h3ykxx.jpg
here they pick intervals as time (not current like in the first example)
why??

4. Aug 27, 2009

### rock.freak667

because they are integrating with respect to time, so the limits must be associated with time. If they were integrating with respect to I, then they'd need limits associated with the current.

5. Aug 28, 2009

### nabliat

why in the first case they integrate with respect to current
and in the second with respect to time

those cases should be calculated in the same way
??