P=IV and P=I^2*R

[jowen88]

---

Members don't see this ad.

when do you use which? I think its I^2*R is for when voltage is constant?

 

[TwoPaddles]

when do you use which? I think its I^2*R is for when voltage is constant?

No, it depends on what you are asked for. You can use both of the equations any time. From what I've seen in my previous practice problems, when they ask for Power, they either give you Work, Force, Time, Current, or Resistance. You have to know either two or three of them in order to find power.

You use P=IV and V=IR in series or parallel circuits. In those problems, you have to understand what's going on: in series, I is the same, whereas in parallel, V is the same.

Keep doing more passages/discretes and you will get used to understanding the difference.

 

[jowen88]

No, it depends on what you are asked for. You can use both of the equations any time. From what I've seen in my previous practice problems, when they ask for Power, they either give you Work, Force, Time, Current, or Resistance. You have to know either two or three of them in order to find power.

You use P=IV and V=IR in series or parallel circuits. In those problems, you have to understand what's going on: in series, I is the same, whereas in parallel, V is the same.

Keep doing more passages/discretes and you will get used to understanding the difference.

not arguing with you, but to paraphrase BR "P=IV is used when voltage is constant and =I^2R when voltage varies"

 

[Rabolisk]

What do you mean when voltage varies? Simply put, you use what you know to get P.

 

[TwoPaddles]

Can you tell me what page it's on? I would like to take a look. But I really don't think it matters which one you use. You end up getting the same units (Watts) anyway.

 

[BillySimmons]

What do you mean when voltage varies? Simply put, you use what you know to get P.

This. Don't overthink it guys. If V is constant (i.e. they give it to you) use p=iv. If not, use the other formulas. Just use what you are given to calculate what you're not.

 

[n3xa]

Penis = In Vagina