1. two identical charges are hung from a desk. Which according to the charge model, which picture is correct?
    1.   choice a
    2.   choice b
    3.   choice c
  2. A negative charge is placed in a cloud of 4 positive charges. Which way will the positive charges move?
    1.   choice a
    2.   choice b
  3. A piece of plastic has a net positive charge. According to the charge model how could this have happened?
    1.   Postive charges were placed on the plastic. leaving it with a net positive charge.
    2.   Negative charges were removed FROM the plastic leaving behind the postive charges.
    3.   Either "a" or "b" is the correct answer.