Drag the charges around the simulation. The arrow on each charge shows the net force on the charge.

Four Charges

Four charges are shown above. How many of them are positive?

  1. One of them
  2. Two of them
  3. Three of them
  4. All four
  5. One or three of them, there's not enough information to decide

Charges 1, 2, and 4 have the same sign, while charge 3 has the opposite sign. There is either one positive charge or three positive charges.

There are two kinds of charge, positive and negative. Like charges repel; unlike charges attract.