Static Electricity Explorer
Rub a rod with a cloth, hang charged spheres side by side, charge a sphere by induction with an earth switch, and trace field lines round point charges.
Learning goals
- state that there are positive and negative charges and that charge is measured in coulombs
- state that unlike charges attract and like charges repel
- Describe an electric field as a region where charge experiences force
- Recall that the field lines of an isolated point charge give the direction of the force on a positive test charge
- Draw the directed electric field of an isolated point charge
Learning objectives
- state that there are positive and negative charges and that charge is measured in coulombs
- state that unlike charges attract and like charges repel
- Describe an electric field as a region where charge experiences force
- Recall that the field lines of an isolated point charge give the direction of the force on a positive test charge
- Draw the directed electric field of an isolated point charge
- Interpret the electric-field pattern between two isolated point charges
- Draw the electric-field pattern between two isolated point charges
- Explain charging by rubbing as electron transfer
- Describe experiments that charge a conductor by induction
A polythene rod is rubbed with a wool cloth. No charge has moved yet.
- Charge moved by rubbing
- 0.0 nC
- Electric force on each sphere
- 0.49 mN
- Distance between centres
- 8.5 cm
- Charge on the sphere
- 0.0 nC
Try this
0 of 4 doneRub the rod with the cloth and compare the charges on them. (not done yet)
Only electrons move. Polythene gains electrons from the wool and acetate loses them to it, so the rod and cloth always end up with equal and opposite charges.
Make a charged sphere attract an uncharged one. (not done yet)
The charged sphere pulls opposite charge to the near side of the uncharged one, so they attract. Attraction does not prove both are charged: only repulsion does.
Charge the sphere by induction so it keeps its charge after the rod is taken away. (not done yet)
Earth the sphere while the rod is near, then break the earth before moving the rod away. The sphere keeps a charge opposite to the rod's: electrons flowed to or from earth.
Put the test charge where two like charges' fields cancel. (not done yet)
At a neutral point the forces from the two charges are equal and opposite, so the test charge feels no force and no field line passes through it.