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# What is this formula? watch

1. My Physics teacher told us the formula below, but didn't say what is was or where it came from so I can't find it anywhere Hopefully someone can help,

is the formula.
2. (Original post by Sora)
My Physics teacher told us the formula below, but didn't say what is was or where it came from so I can't find it anywhere Hopefully someone can help,

is the formula.
It's a formula associated with alternating current and expresses how current varies sinusoidally.

I is current at time t
Io is peak current
ω is a constant and related to the frequency f of the current in the same way as in simple harmonic motion, which you may be familiar with.

f = ω/2π

It seems odd being given this for no apparent reason and with no explanation.
3. (Original post by Stonebridge)
It's a formula associated with alternating current and expresses how current varies sinusoidally.

I is current at time t
Io is peak current
ω is a constant and related to the frequency f of the current in the same way as in simple harmonic motion, which you may be familiar with.

f = ω/2π

It seems odd being given this for no apparent reason and with no explanation.
So when and why would I use this? It's not in my textbook and I can't find it in the syllabus either...
4. Is this A-Level because I'm doing GCSE and I've never seen this before. My exam is in 3 days so I'm getting kinda worried!
5. (Original post by SaiDuc)
Is this A-Level because I'm doing GCSE and I've never seen this before. My exam is in 3 days so I'm getting kinda worried!
Aha no need to worry! I'm certain it's A level or higher good luck though!
6. (Original post by Sora)
So when and why would I use this? It's not in my textbook and I can't find it in the syllabus either...

It's a formula you use with alternating current circuits.
If it isn't in the specification then forget it.

It may be your teacher wanted to point out how it's similar to the equation for a wave, or the connection with SHM.
As I say, ask your teacher. Only he/she can know what the point of this was.
7. You might not need to do any of the maths. When you do, there are all sorts of complicated effects which I don't recall being on the A-level syllabus.

However, you do need to know qualitatively what happens when you have an oscillating current - such as for example in a transformer or an AC motor. Perhaps your teacher only wrote down the formula because it's a general representation of an AC current, and didn't expect you to have to do anything with it.

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