Doesn't the acquired charge on the insulator also get polarized? I was wondering that in experiments such as comb attracting tiny paper pieces or a charged balloon sticking to the wall.
The comb and balloon acquires negative charge that is localized on the surface and the electric field due to that negative charge polarizes paper/wall which results in attraction , but my doubt was whether polarization of paper/wall will not effect the distribution of negative charge on the comb/balloon ?
Paper/walls are also insulators but they get polarized so why not the comb or balloon for that matter ?
It would've be great if anybody could help me out considering I had just started upon electrostatics.
 A: Although induced dipoles can experience a force in an exterior field (that of the balloon or comb) they are very bad at generating a field themselves. This is due to the fact that the fields of two opposite charges in close proximity (i.e. in a dipole) almost cancel. As a result the electric field strength of a dipole is proportional to $1/r^3$ while the electric field strength of a monopole (single charge) is proportional to $1/r^2$ where $r$ is the distance from the source.
This is the reason why you can often neglect the fields of dipoles if significant net charge is also present at the same time. Nevertheless, there actually is an effect, even if it is small. In the case of the balloon: it will mainly be polarized by its own charges, but it will also be polarized (to a very small extent) by the dipoles in the wall. This is why you strictly only can solve the problem of both media being polarizable, which is done by Maxwell's equations in matter.
By the way, dipoles only experience a force in an inhomogeneous field. For the localized charges of the balloon or comb this inhomogeneity is given. But, if you ever have to do with dipoles in a homogeneous field (e.g. a capacitor), don't be surprised to find no force. In a homogeneous field, dipoles only experience torque, and only if they are oriented at an angle to the field. This could be the case e.g. for permanent dipoles or induced dipoles in an non-isotropic medium.
A: Indeed the polarization of the paper/wall does affect the charge distribution on the balloon/comb. But the balloon/comb still carries an overall negative charge.
The key point here is that the paper's/wall's polarization cannot be strong enough to overcome the effects of the overall charge on the offending comb/balloon and repel it (think about what would happen to the paper's/wall's polarization if it did). In fact, since the paper/wall and the comb/balloon are insulators, we can't even get close. The best we'll be able to do is make the comb/balloon a little less negative near the paper/wall, and a little more negative far from the paper/wall.
You can think of an insulator as consisting of lots of little pairs of charges, one positive and one negative, stuck together by a fixed rod and (as a pair) locked in place. We call these pairs 'dipoles.' A conductor, by contrast, also consists of lots of little pairs, but no rods connecting them or fixing them in place -- the charges in the pair are free to flow apart and redistribute themselves throughout the conductor.
When an insulator is polarized by, say, an external negative charge, these dipoles rotate so that the positive member of the pair is toward the external charge, and the negative member is away from it. Now imagine a line of these dipoles arrayed end to end, with an external negative charge at one end of the line. The dipole closest to the negative charge reorients as described, which presents a positive charge to the next dipole. That dipole reorients and presents a positive charge to the following dipole, and so on down the line until the dipoles form a line of alternating negative and positive charges, with a negative charge at one end and a positive charge at the other. This makes it look like a positive charge has moved to one end of the line and a negative charge has moved to the other end, though in fact the charges haven't moved very much at all. But out of all those charges, the net effect is the motion of a single charge, not enough to counteract the effect of the external charge.
Conversely, in a conductor, each of those charges would be free to flow as far as it wants, and so they flow until there is no more force acting on them -- i.e. when they've canceled the field of the external charge within the volume of the conductor.
So our balloon polarizes the wall and our wall polarizes the balloon, but not enough to make the balloon look positively charged near the wall. So they stick together.
