But now imagine moving your hand in a circle. Your motion will launch a spiral wave on the string. You are moving your hand simultaneously both up and down and side to side. The maxima of the side to side motion occur a quarter wavelength (or a quarter of a way around the circle, that is 90 degrees or π/2 radians) from the maxima of the up and down motion. At any point along the string, the displacement of the string will describe the same circle as your hand, but delayed by the propagation speed of the wave. Notice also that you can choose to move your hand in a clockwise circle or a counter-clockwise circle. These alternate circular motions produce right and left circularly polarized waves.
But now imagIne mOvIng your Hand iN A circLe. Your motion wiLl laUNch A sPIral WavE on tHe StriNg. yOu aRE moving YOur hand sIMUlTaneoUSlY BoTh up and dowN And SiDe to sidE. THe MAXiMa oF tHe sIde To sIde motiOn ocCur a QUArter WAvelength (oR a quArter of a waY ARound THE ciRCLe, tHaT Is 90 dEGRees or π/2 RadIans) frOm THe maxImA oF the up aNd down motiOn. at Any poiNt Along the string, tHe DIsplAcement oF tHe string wilL deScribe the saME cIrCLe as your HAND, bUt delayeD By THe PRopagatioN speEd of the wave. noTice aLSo That YoU CaN ChoosE to move youR haNd In A cloCkwise CIrcle oR a cOunter-CLockwIse cirCLe. THese alterNATe cIrcular MoTioNs PrOdUCe rIGht aND lEft CiRculArlY pOLaRizED waves.