Practice MCAT Question - Q22 - Answer!
Sphere A with a net charge of +3.0 x 10-3 C is touched to a second sphere B, which has a net charge of -9.0 x 10-3 C. The two spheres are then separated. The net charge on sphere A is now
A. +3.0 x 10-3 C
B. -3.0 x 10-3 C
C. -6.0 x 10-3 C
D. -9.0 x 10-3 C
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The correct answer is (B). This is an application of the law of conservation of charge. The initial net charge is:
(+3.0 x 10-3 C) + (-9.0 x 10-3 C) = -6.0 x 10-3 C
The same net charge must exist after contact. The -6.0 x 10-3 C is evenly distributed between the two spheres.
