Who’s right? The atom is negative because the electrons are on the outside The atom is neutral because the opposite charges balance each other out Taking away an electron will drag a proton too because opposites attract Can’t you see the electrons can’t touch the protons? Come on, opposites repel!

Attracting uncharged objects Electrostatic induction Electric dipole

Electrostatic induction Last lesson we saw: That like charges repel each other and unlike charges attract each other. That materials with a negative charge have an excess of electrons and materials with a positive charge have a deficiency of electrons. That an acetate rod charged positively can attract neutral objects like light chips of paper. But how can a charged object attract uncharged objects like the bits of paper?

Electrostatic induction Let’s have a look at a single atom inside the piece of paper The atom is neutral because the cloud of electrons (in blue) around the nucleus is distributed in a way that cancels out the effects of the positive charge in the nucleus (red sphere). Draw a blue arrow to show the force the electrons in the cloud will be affected by and a red arrow to show the force on the nucleus of the atom when a charge is approaching. That’s right! The electrons will move towards the positive charge and the nucleus away from the positive charge. What do you think will happen to the electron cloud and to the nucleus of the atom when a positive charge is near them? The distribution of electrons around the nucleus is shifted and does not balance the positive charge of the nucleus anymore. This new configuration of the atom is called ELECTRIC DIPOLE.

All the atoms/molecules of the piece of paper will undergo the same process. So, the electric force from every dipole will add up to lift the paper to the rod. Electrostatic induction This is called ELECTROSTATIC INDUCTION

Quick test on electrostatics. a The force between like charges is… Repulsive Dipole Deficiency Electrostatic induction Negative Electrons Attractive Positive The same b.This is the name of an atom with shifted electron cloud! c A positively charged item has a ……………of electrons! d This is when a charged object attracts an uncharged one! e The charge on a polythene rod when rubbed. f Which particles move when an object gets charged? g The force between unlike charges is… h These are the charges that don’t move. i The atom is neutral because the number of protons and the number of electrons is… j The charge on an acetate rod when rubbed.