Answer
No, it does not mean that there are no negative charges inside. It can mean that the magnitude of positive charges is more than the negative charges.
E.g. :- a conductor with 2 cavities inside, one with positive charges and other with negative charges inside, the positive charges being more than the negative ones, then the net number electric field lines points outwards from a Gaussian surface.
Work Step by Step
No, it does not mean that there are no negative charges inside. It can mean that the magnitude of positive charges is more than the negative charges.
E.g. :- a conductor with 2 cavities inside, one with positive charges and other with negative charges inside, the positive charges being more than the negative ones, then the net number electric field lines points outwards from a Gaussian surface.
