Answer: Zero.
- A kQ/r<sup>2</sup>
- B kQ/R<sup>2</sup>
- C Zero
- D kQr/R<sup>3</sup>
Correct answer: C. Zero
Explanation: Shell theorem: the electric field inside a uniformly charged spherical shell is zero. All charge is on the surface.
Field lines always point from positive to negative charge, are denser where the field is stronger, and never cross; an isolated positive charge has lines radiating symmetrically outward, while a dipole's lines curve from the positive to the negative charge.
Concept context
Coulomb's law, electric field, potential, capacitors, Gauss's law.