Two small objects are suspended from threads. when the objects are moved close together, they attract one another. what of the following could produce this result? a. on object is positively charged and the other is negatively charged. b. one object is positively charged and the other conductor is uncharged. c. one object is negatively charged and the other conductor is uncharged. d. all of the above could result in an attraction.

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.