What is the minimum magnitude of an electric field that balances the weight of a plastic sphere of mass 6.4 g that has been charged to -3.0 nC?

Question

Quizplus · Accepted Answer

The electric force on the charged plastic sphere is given by:
F = qE
where q is the charge on the sphere and E is the electric field.

To balance the weight of the sphere, the electric force must be equal in magnitude and opposite in direction to the force of gravity. The weight of the sphere is given by:
W = mg
where m is the mass and g is the acceleration due to gravity.

Equating the two forces, we get:
qE = mg

Solving for E, we get:
E = mg/q

Substituting the given values, we get:
E = (6.4 x 10^-3 kg)(9.8 m/s^2)/(3.0 x 10^-9 C)
E = 2.1 x 10^17 N/C

Therefore, the minimum magnitude of the electric field required to balance the weight of the charged plastic sphere is 2.1 x 10^17 N/C, which corresponds to choice A.

What Is the Minimum Magnitude of an Electric Field That