Answer: F = kq1q2/r2.
- A F = kq1q2/r
- B F = kq1q2/r2
- C F = kq1q2*r2
- D F = k(q1+q2)/r2
Correct answer: B. F = kq1q2/r2
Explanation: F = kq1q2/r2 where k = 9 x 109 N m2/C2. Force is proportional to product of charges and inversely to r2.
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.