00:01
I told we want to power a certain number of 500 watt lamps with a 120 -fold power source, and there's a fuse in here that can handle the maximum of 15 amps or blow out.
00:18
So they ask us how many of these lamps can we power? so each one of them is going to have a resistance, and so we're putting them all in parallel.
00:31
So we have, you know, n of them here.
00:35
And so the equivalent resistance of this whole thing is r over n, just because they're all the same resistance, and they're all in parallel.
00:47
The current through here, through the battery, and through the fuse, is v over this equivalent resistance, or n times v over r.
00:59
You also know that each one of these lamps has the voltage drop across it is v, so the power is v squared over r.
01:11
So r equals v squared over p.
01:14
So we can plug that into here.
01:17
And we get that the current is p times n all over v, or n equals v times i all over p.
01:26
And that comes out to be v times i over p comes out to be 3 .6...