An unknown blue charge (#1) is shot into a region containing four fixed charges, one of which is known to be positive (the red one).
Determine the signs of the unknown charges. You may consider neutral as a possible answer. Start (Pause)
Charge 1: negative / Charge 2: neutral / Charge 3: positive / Charge 4: negative.
See Giancoli-PA: 16-7, Giancoli-SE: 21-6.
Physlet problem authored by Scott Bonham.