00:01
In this question, we are trying to fix a transformer for a toy truck, and it looks like the toy truck uses 8 volts of emf to run, and the primary coil of the transformer is broken, and the secondary coil has 30 turns.
00:18
So let's organize our information.
00:21
We know that the toy truck will use an emf of 8 volts, and this will be my secondary emf because it is not the source voltage, it tells us that the primary coil is broken, so we don't know how many turns there are in the primary coil, but we do know that the secondary coil has 30 turns, so n -sup -s is 30.
00:45
And we do also know the primary voltage source, which is 120 volts, according to the question.
00:55
Now, part a asks us, how many turns would you have in the primary coil? and so in order to figure this out, we set up our ratio.
01:05
We know that because the primary and the secondary coils in an ideal transformer should have the same change in magnetic flux over time.
01:15
And so by rearranging faraday's law of induction, we can also set equality between these two ratios, which is emf of the primary coil to the number of turns in the primary coil equal to the emf, of the secondary coil, divided by the number of turns in the secondary coil.
01:37
So once we have this equality set up, the rest is simply algebra...