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physics213
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Homework Statement
A ping pong ball covered with a conducting graphite coating has a mass .005 kg and a charge -4 microC. What electric field will exactly balance the weight of the ball?
Homework Equations
qE = mg
The Attempt at a Solution
I know how to get the magnitude of the electric field using the equation above. I just don't understand the conceptual part of this question: Which way is the electric field going (up or down)? Any help would be appreciated...thanks