**The Root Mean Square**(

*R.M.S)*value of a voltage or current is:

V

_{RMS}= V

_{P}/ Ö2 and I

_{RMS}= I

_{P}/ Ö2

where V

_{RMS}and I

_{RMS}are the R.M.S. values, and V

_{P}and I

_{P}are the peak values.

Ö2 » 1.414

Similarly, multiply R.M.S. by Ö2 to get the peak value.

Values quoted are R.M.S. unless otherwise stated - normally the R.M.S. subscript is left off.

E.g. 240V A.C. mains has a peak value of 240 X Ö2 = 340V peak.