We learned from the beginning at the university that RMS = peak-peak/root(2)
Just wondered what is the logic behind this dividing of root 2. Can anybody explain the root logic behind this?

Square root of 2 is 1.414 . The reciprocal is 1/1.414 = 0.707. This factor of 0.707 multiplied by the peak to peak magnitude of a sinusoidal current or voltage will give you the RMS magnitude / value. This RMS value is the "effective" value of the sinusoidal current or voltage. This effective value in terms of power is the effective power. When you are measuring sinusoidal voltage or current, you are interested to get the effective (RMS) magnitude, not the peak to peak magnitude. The RMS is the one that provides the power to do the work. Example: The heating effect produced by a current flowing aross a resistance is:Current I (RMS) squared multiplied by the resistance. It is the RMS value, not the peak to peak value that provides the effective heating power.

Actual it is Vp/(2)^.5 or Vp(.707), best I could do on my cell.

RMS is the integral of any waveform over a period of time. The above only works for sinusoidal wave form.

Check out wikipedia for excellent detailed step by step analysis until its reduction to above formula.

Cheers

@Meynardo
nice explanation well but I have also seen sometimes we divide the value by 2 and sometimes by root 2. can you differentiate both?
in which cases it is done?