22.4
Rub a plastic rod against fur to charge it negatively.
Take a conducting metallic sphere supported by an insulating plastic stand.
When the charged rod is brought close to the neutral sphere, free electrons inside the sphere are repelled away from it.
As more free electrons try to move, they are also repelled by those already moved. The electrons distribute such that there is no net force on any free electron.
More free electrons have accumulated on the far end of the conductor, leaving the closer end carrying a net positive charge. The two poles are oppositely charged or polarized. Such a charge distribution is called a dipole.
If the sphere is connected to the Earth via another metallic wire, the free electrons move to the Earth. When the wire is removed, the sphere carries a net positive charge. This process is called induction.
The negatively charged plastic rod does not lose or gain any charge. Induction results in a charge exchange between the conductor and the Earth.
de Aarde is een goede geleider van elektriciteit en is zo groot dat ze kan worden beschouwd als een oneindige bron of put van ladingen. Het kan gemakk…
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