Question

While assembling a system of charges, the work done in bringing the first charge \[q_1\] from infinity to its Position 1 is:

Options

• \[W_1 = \frac{1}{4\pi\varepsilon_0}\frac{q_1^2}{r}\]

• \[W_1 = \infty\], because the charge starts from infinity

• \[W_1 = 0\], because no other charge is present to exert a force on it

• \[W_1 = q_1 \times V_1\]

Answer 1

The first charge \[q_1\] experiences no force while being brought in, since no other charge is present in the region. Hence \[W_1 = 0\], and only the subsequent charges contribute interaction work to the potential energy.