AP Physics C E&M 10.2.A Charge Redistribution on Contact

Practise predicting how charge moves when conductors touch by applying charge conservation, equal electric potential, conductor size, and contact-force effects.

Exam points

Conserve total charge and set connected conductors to equal potential to find each final charge.
Use V=kQ/R to determine how conductor radius sets the charge ratio at equilibrium.
Track charge polarity after contact with a plate to predict the resulting attraction or repulsion.

[Maximum number: 1]

Conducting spheres 1 and 2 on insulating stands have radii 2 R and R, respectively. The spheres are very far apart. Sphere 1 has an initial net charge +Q and Sphere 2 is initially neutral. The spheres are then connected by a conducting wire, as shown. The wire is then removed. Which of the following represents the value of the net charge on Sphere 1 after the wire is removed?

$\frac{1}{2} Q$

$\frac{2}{3} Q$

$\frac{3}{4} Q$

$\frac{4}{5} Q$

Figure for Question 10.2.A—Describe the movement of charge and the resulting interactions when conductors physically contact each other question 1 — AP Physics C: Electricity & Magnetism

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10.2.A—Describe the movement of charge and the resulting interactions when conductors physically contact each other question 1