posted by Valerie .
A speck of charged dust with a mass of 39mu g. is kept levitating by putting it in an electric field. If you must apply a field of 10 N/C to keep it suspended in mid-air, what is the charge on the speck of dust?
Can someone please help soon? I got this wrong on my last test because I'm terrible at physics and I'm trying not to make the same mistake on the exam. An explanation would be great.