Electric Field Lines: Charge Movement and Conductor/Insulator Interactions

[KodN919]

1. The problem statement
"If charges are free to move, the field lines will straighten and shorten as the charges move together"

2. Questions in relation to statement
Are there any cases in which charges aren't free to move between two charged objects such as between conductors or insulators?
And how do charges move 'together' in electric field lines?

 

[haruspex]

1. The problem statement
"If charges are free to move, the field lines will straighten and shorten as the charges move together"

2. Questions in relation to statement
Are there any cases in which charges aren't free to move between two charged objects such as between conductors or insulators?
And how do charges move 'together' in electric field lines?

By definition, charges are free to move within a conductor but not within an insulator.
You can regard an air gap as an insulator.
If two charges are (can be thought of as being) connected by a field line and one is free to move in that direction it will accelerate along the field line towards the other.

 

[KodN919]

By definition, charges are free to move within a conductor but not within an insulator.
You can regard an air gap as an insulator.
If two charges are (can be thought of as being) connected by a field line and one is free to move in that direction it will accelerate along the field line towards the other.

Thank you very much