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Gajan1234
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There are three Formulas for Power, ( P=IV, P=I^2R, P=V^2/R). Can someone tell me when to use the right forumlas?
It is quite confusing in the book as they have used different formula for different question. But I know that P=I^2R is used to find the heatProfuselyQuarky said:How has your textbook explained it?
Okay, well, do you know what each variable stands for?Gajan1234 said:It is quite confusing in the book as they have used different formula for different question. But I know that P=I^2R is used to find the heat
Dale said:What are your thoughts? What is different about the three equations and when might those differences be important?
I for currentProfuselyQuarky said:Okay, well, do you know what each variable stands for?
OK, that is a good start.Gajan1234 said:I think that P=IV is mainly used to find the power of the whole circuit whereas P=I^2R is used to find how much energy is given out by the component per second.
But not sure if I am right.
Dale said:OK, that is a good start.
What is different about P=I^2 R that makes it better for individual components than P=IV?
Right. So would it be possible to use P=I^2 R if you don't know the resistance?Gajan1234 said:Well we are looking at difficulty of current going through due to resistivity.
Not really It just depends on what you're looking for--and the only way to know what you're looking for would be to know what each part means. Perhaps this picture will help: click hereGajan1234 said:But when it come to practice questions it is used differently in different context
Dale said:Right. So would it be possible to use P=I^2 R if you don't know the resistance?
That's correct! See, you can use different equations (in this case, Ohm's Law) to find the missing parts you need. So where's the trouble?Gajan1234 said:Well it is possible if you know the voltage
Yes, exactly. There are only two formulas here: P=IV and V=IR. You have two equations in four variables. You can always substitute one equation into the other to eliminate anyone variable.Gajan1234 said:Well it is possible if you know the voltage
Dale said:Yes, exactly. There are only two formulas here: P=IV and V=IR. You have two equations in four variables. You can always substitute one equation into the other to eliminate anyone variable.
That is all those ewuayions do. You are then left with one equation in three variables. Use the one that fits.
Dale said:Yes, exactly. There are only two formulas here: P=IV and V=IR. You have two equations in four variables. You can always substitute one equation into the other to eliminate anyone variable.
That is all those ewuayions do. You are then left with one equation in three variables. Use the one that fits.
What are the knowns and what are the unknowns? Which formula fits?Gajan1234 said:If you look ag question 3c you can not use all the formulas. Only one will give you the right answer.
And based on that, which formula for power matches what you know?Dale said:What are the knowns and what are the unknowns?
P=v`2/rProfuselyQuarky said:And based on that, which formula for power matches what you know?
This gives me the wrong answerGajan1234 said:P=v`2/r
What numbers did you use?Gajan1234 said:This gives me the wrong answer
Well I can use the P=v^2/R formula but it gives me the wrong answerDale said:What are the knowns and what are the unknowns? Which formula fits?
P=6^2/9ProfuselyQuarky said:What numbers did you use?
Why did you use "6" for volts? The picture's not that clear, but doesn't it read "3"?Gajan1234 said:P=6^2/9
When? Always, always use the right formulas!Gajan1234 said:There are three Formulas for Power, ( P=IV, P=I^2R, P=V^2/R). Can someone tell me when to use the right forumlas?
Power formulas are used to calculate the amount of power or energy used or produced in a given system. They can also be used to determine the efficiency of a system.
Power formulas should be used when there is a need to quantify the amount of power or energy in a system, or when comparing the efficiency of different systems.
Some common power formulas include P = VI (power equals voltage multiplied by current), P = I2R (power equals current squared multiplied by resistance), and P = V2/R (power equals voltage squared divided by resistance).
The power formula to use depends on the specific situation and the variables that are known. For example, if you know the voltage and current, you can use the formula P = VI. It is important to understand the relationship between the variables in order to use the correct formula.
Yes, power formulas can be applied to any system as long as the variables and units are consistent. However, some systems may have more complex power formulas that take into account additional variables.