Question

When bringing charge q₁ from infinity to position r₁ in an external electric field, what is the work done against the external field?

Options

• \[W_1 = \frac{q_1}{V(r_1)}\]

• \[W_1 = \frac{V(r_1)}{q_1}\]

• \[W_1 = q_1E(r_1)\]

• \[W_1 = q_1V(r_1)\]

Answer 1

The work done against the external field to bring a charge q₁ from infinity to position r₁ is equal to the product of the charge and the external potential at that position. This work is stored as the potential energy of q₁ in the external field.