00:01
When we have a hair dryer that has an output of 1 ,500 watts and an emf, epsilon of 120 volts.
00:15
So for part a, we want to find the resistance of this hair dryer.
00:22
So we know that power is equal to the current flowing through the hair dryer times its emf.
00:30
And in other words for emf is the potential difference.
00:35
It's just its ability to move charges from the negative terminal of the battery to the positive terminal or the highest potential in the battery.
00:47
So since charges are flowing inside of the battery, there has to be a current.
00:51
So we know that current here will have some sort of value.
00:54
So if we look at current, we know that from holmes law, we get a delta, be the potential difference is equal to the current times the resistance selfie saw for the current we have current is equal to potential difference divided by the resistance so if we plug that in to power we get power is equal to potential difference divided by r times the emf but in a battery the emf is similar to the potential difference.
01:47
So if we just replace v with epsilon, we now get power.
01:58
Power is equal to the emf squared divided by the resistance.
02:10
So then now we can solve for the resistance.
02:18
So we get r is equal to the emf squared divided by power...