I've heard that a changing electric field creates a magnetic field and a changing magnetic field creates an electric field, but I am still very confused about exactly how this propagation actually works. The visual representation of an electromagnetic wave I have seen are a sinusoidal electric and magnetic field waves travelling in the same direction, but a line connecting the electric waves peak and trough would lie perpendicular to the magnetic fields peak and trough. These lines would also lie perpedicular to the direction the wave is travelling. It looks like this: http://ffden2.phys.uaf.edu/webproj/212_spring_2014/Amanda_Mcpherson/Amanda_McPherson/em_electric_magnetic_propagating_waves.jpg [Broken] At this point I am already confused. To my knowledge, an electric field exists at all points in space with different intensities. It is a scalar quantity. How then, can this field be 'waving' in a sinusoidal pattern through space?