Like charges repel each other and unlike charges attract. An electric charge experiences a force whenever it is placed in an eletctric field.
Electric field is a vector quantity.
The direction of the electric field is the direction of the force on a positive charge when placed in the field. When a charge q is moved in a electric field, work must be done. Electric potential is a scalar quantity. This is a device for producing very large static voltages. Click here for a sketch of a VDG generator, and here to see a photograph.