Question

How is rms value of AC voltage related to peak value of AC voltage

Answer 1

Peak values can be calculated from RMS values from the formula, which implies
Vp = Vrms × √2,
assuming the source is a pure sine wave.

In statistics and its applications, the root mean square (abbreviated RMS or rms) is defined as the square root of the mean square (the arithmetic mean of the squares of a set of numbers). The RMS is also known as the quadratic mean and is a particular case of the generalized mean with exponent 2. RMS can also be defined for a continuously varying function in terms of an integral of the squares of the instantaneous values during a cycle.

For alternating electric current, RMS is equal to the value of the direct current that would produce the same average power dissipation in a resistive load.

In estimation theory, the root mean square error of an estimator is a measure of the imperfection of the fit of the estimator to the data.
Peak value of AC voltage is root 2 times the rms value of AC voltage.