Answer: kQ/r2 (same as point charge).
- A kQ/r2 (same as point charge)
- B kQr/R3, the formula valid mainly for points inside the sphere
- C Zero, as if the field vanished largely outside the shell
- D kQ/R2, using the sphere's own radius instead of the distance r
Correct answer: A. kQ/r2 (same as point charge)
Explanation: Outside a uniformly charged sphere, field = kQ/r2 (same as if all charge were at center: shell theorem).
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.