Insulators like plastics can collect a charge through friction and the transfer of electrons, but this charge cannot be transferred and is therefore static. The material which gains electrons becomes negatively charged while the material which loses electrons has an equal positive charge. There is a force of attraction between unlike charges and a force of repulsion between like charges.
A charged object can affect the distribution of charges on an uncharged object. If a negatively charged balloon is brought towards a wall, the electrons in the wall are repelled and a positive charge is left behind, attracting the negative charge on the balloon. This is called charging by induction.
People can get shocks from everyday objects. If a person walks along a carpet, the charges in the person may end up unbalanced. When touching a conductor, the electrons will flow between the person and the conductor in a spark. This will result in the feeling of a shock as the person is discharged
Static electricity builds in clouds doe to friction between particles of ice and water moved by currents. When the charge is large enough, charged particles move through the air to the earth, causing thunder and lightning.
Sparks can be dangerous, such as when fuel vapour could ignite. This can be an issue in aircraft refuelling, which become charged in flight. To prevent a spark between the fuel pipe and the aircraft, a bonding line is connected to the earth before refuelling. Earthing removes excess charge by movement of electrons. This principal is also seen at petrol stations where pipes are earthed. Cars are earthed through their tyres.
Electrostatic spraying uses static electricity. When spraying crops with insecticide, electrodes on the spray nozzle charge the droplets as they pass. These droplets then spread out as they repel each other, and they are attracted to the crop by induction. Less insecticide is wasted and less enters the ecosystem
An electric field is the region where an electric charge experiences a force. The lines go from positive to negative and the more concentrated the lines, the stronger the field is. Between two parallel plates, the field is uniform.
Induced charges can be strong enough to move charged objects, with the field, and this concept can show how static electricity works.