JiTT at FIE, Indianapolis, 2005

	Just-in-Time Teaching FIE, October 21, 2005

Question

Can there be an electric field at a point where there is no charge? Can there be a charge at a place where there is no field? Please write a one or two sentence answer to each of these questions.

Answers

Yes. There can be an electric field where there is no charge. Some charge at some other location can produce an electric field at this point.

No. Any time there is a charge it creates an electric field in its vicinity.

Yes, because an electric field is produced from a charged object and the field is present in the vicinity of that object.

No, because a charged object produces an electric field, therefore, no field is present.

There can be an electric field at a point where there is no charge. There must be a charge to create the field, but the charge does not have to be at that point, there is an electric field in the area around the charge.

There cannot be a charge at a place where there is no electric field because the charge would create an electric field.

Yes; Electric fields depend on the charge of source and distance. A second charge is not needed. For example, a electric field could permeate through a vacuum. By it's very nature, no charge could exist in that vacuum other than the source.

Yes; If you have only one charge, that one charge will create an electric field around itself, but not including itself. Therefore, the charge would be at the center where there is no field.