What is meant by phase of a wave? I can't get a grasp of it especially after knowing that in an em wave ,the magnetic and electric fields E and B respectively are in phase , aren't they time varying and perpendicular to eachother? Doesn't changing the inclination affect the phase ? Also,the phase difference ,I can't get it(this may sound stupid) when phase difference=0,does that mean that,say the 2 waves I'm measuring their phase diff. Are in phase ? And what are the possible equations by which I can determine the path difference between 2 waves? Thanks in avance !