Subject: Why don't magnetic and electrical field lines overlap?

As seen from a magnetic field lines diagram, why don't the lines overlap 
one another and this also goes the same for electric field lines? Another 
question is when a highly positively-charged anode (a cylinder with a very 
narrow hole at the center) is placed in front of a hot filament emitting 
electrons, why are the electrons concentrated into a narrow beam after 
passing through the hole of the anode?
Thank You!

Re: Why don't magnetic and electrical field lines overlap?