# Why magnetic and electric field obey Helmholtz equation?

I am trying to understand the basic principles of scalar diffraction theory and came across the sentence "E and H obey the Helmholtz equation", what does that mean? Does that mean that each component of E and H field obey the same equation?

• Since you mention wanting to understand scalar diffraction theory, my question received some good answer (although not 100% satisfying), have a look: physics.stackexchange.com/questions/311102/… Jun 26 at 11:19

Yes. First, $$E$$ and $$H$$ (each separately) obey the same wave equation which says nothing else that the $$E$$ wave travels with the speed of light and has the same wavelength as the $$H$$ wave which, too, travels with the speed of light. The Helmholtz equation is obtained from the wave equation when one separates space and time variables to find particular solutions.