suppose we have two sinusoidal voltages of the same frequency with rms values of 10v and 7v, respectively. The phase angles are unknown. What is the smallest rms value that the sum of these voltages could have? The largest? Justify your answers.

The answer is 17v and 3 v. But i thought it would be 17v and -17v. Its an easy question. just don't see the logic

Check the definition of rms voltage. Obviously what you have in mind is wrong because -17V is not acceptable.

@jadefalcon we have two sinusoidal voltages of 10 and 7 volt rms We don't know anything about their phase, If they are added, max voltage will occur when they are in same Phase, minimum will occur when they are are of opposite phase( i.e they have a phase difference of 180 degrees) |dw:1338117480959:dw|

Join our real-time social learning platform and learn together with your friends!