00:01
Okay, so for this one, we have a battery, resistor, and inductor, usual characters.
00:06
And then we're given the inductive time constant.
00:10
It's 37 milliseconds.
00:11
I'll go ahead and write that down.
00:14
Oops, i'll call that tau, not t.
00:21
37 times 10 to the minus three seconds.
00:26
And, yeah, let's see what else is going on.
00:28
And we want to know when the energy dissipated in the resistor is equal to the energy rate at which the energy is stored in the inductors magnetic field.
00:38
Lots of words, just some calculus, though.
00:42
So, yeah, so the power, so basically the power through the resistor, let's see, energy dissipated in the resistor is the power of through the resistor, and that's i squared of times r.
01:04
So we can say p is i squared r and then we want to set this equal to the energy through the derivative of the energy through the inductor.
01:17
So i'll kind of put this up here.
01:20
The energy stored in an inductor is l i squared and if you take a derivative of this with respect to time if l stays constant i just changes so then you have you want to be setting that equal to l -i -d -t.
01:38
Great...