Hello, the R.M.S. value of a current i(t) composed of several sinusoids of different frequencies and any phase angle is given by: Irms=SQRT(I1rms2 + I2rms2 + I3rms2 + .... + INrms). The expression holds equally well for r.m.s. voltage too. It is asked to find the r.m.s. value of the following voltage: v(t) = 6cos(25t) + 5sin(30t) + 4 V. The solution is 6.82 Vrms. How does one account the d.c. 4 volt into the equation. In the absence of this d.c. voltage component, i.e. considering only the two sinusoid components, the formula gives 5.523 Vrms. But how to account the 4V component to obtain 6.82 Vrms as the r.m.s. value? Help is sought.
