What is in the space between magnetic or electric field lines? Is the field continuous and if so why do things like iron filings tend to line up on these "imaginary lines"?

Question

What is in the space between magnetic or electric field lines?  Is the field continuous and if so why do things like iron filings tend to line up on these "imaginary lines"?

anonymous · Answer

magnetic or electric field lines actually donot exist. they are actually a way of representing the electromagnetic force in a region. and hence there is no space between field lines. 
Iron filings tends to line up along electric field lines not beacause they are lines but these lines represents the direction of force acting on particles and the direction of force determines the direction of orientation of iron filings