Why are there dust particles on TV screens? My professor gave us the following reason:

The screen is positively charged. When dust particles fly near it, the positive charges in the screen induce a charge in the dust particle, pulling the negative charges closer to it, and pushing the positive charges away. The screen then attracts the negative side, pulling the dust particle to it.

But why does the screen attract the whole dust particle? Its only attracting the negative charges so why does the "whole" dust particle go to the screen? Why doesn't the screen just rip out the electrons, and repel away the rest of the particle? 
 A: When the electric charge on the dust particle is induced, it is attracted to the TV screen.  The dust particle is a solid, the electric charge induced the TV screen, can (or not) move the particle (this depends on the particle itself), but the charge can't leave the solid structure of the particle and "float" in the air to the TV screen, because the amount of energy required to leave the solid is extremely high.  Instead, the electrostatic force continues to act in such a way that attracts the whole particle.
Furthermore, because the outside of the screen is made of glass, attracted charged particles can not compensate the charge of the screen (which is on the inside) because there is no electrical path in the glass, that is why remain attached to the screen.
A: Short answer:Finite size of dust particles and inverse square law.
The side of the dust particle towards the screen is negatively charged and the other side is positively charged.Now due to the inverse square law,the force of attraction is more than than the repulsion as the negative side is closer and the particle experiences a net force towards the screen.

Why the electrons don't travel to the screen?
Because they still tightly held by the atoms of the dust particle.The T.V. screen only induced a slight polarization of the dust particle.The electrons have not travelled to the negative side(unlike conductors) but the atom itself undergoes slight polarization.(Similar to what happens in dielectrics). 
A: Dust tends to remain suspended in air for long periods, which would imply that it is made of relatively light elements, carbon, sodium, silicates, etc. Most of these lighter elements apply a stronger force to their electrons, because they have less electron shells. This makes the force required to get them to shed electrons exponentially higher. Heavier elements like copper, zinc and lead give up electrons more easily, but wouldn't tend to stay suspended in air due to their greater mass. 
A: the positively charged particles attracted the negatively charged particles so when dust particles fly near the t.v. screen.the screen induces the charge in the dust particles pulling negatively charged particles closer to it.
