# Question Video: Calculating the Root Mean Square Value of Current Physics • 9th Grade

An alternating current has a peak value of 1.35 A. What is the root-mean-square value of the current? Give your answer in three decimal places.

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### Video Transcript

An alternating current has a peak value of 1.35 amperes. What is the root-mean-square value of the current? Give your answer in three decimal places.

Here, we have an alternating current. So, if we were to plot its value as a function of time, we would see that it’s always fluctuating between some positive and negative peak value. In this question, we’ve been told that the peak value is 1.35 amps. And recall that we can determine the root-mean-square value of an alternating current using the formula one over the square root of two times the peak current.

We already know the peak current. So let’s substitute it into the formula. And we have one over the square root of two times 1.35 amperes, which comes out to 0.95459 and so on amps. Finally, rounding our answer to three decimal places, we’ve found that the root-mean-square value of the alternating current is 0.955 amperes.