Answer:
![B = 2.5 * 10^(-18) T](https://img.qammunity.org/2020/formulas/physics/high-school/m5chuynb99x8vbb7b8l28uk3vvgprevvqe.png)
Step-by-step explanation:
Magnetic field due to moving electron is given by the formula
![B = (\mu_0 qv)/(4\pi r^2)](https://img.qammunity.org/2020/formulas/physics/high-school/son1nojgm1jur74o3zfy9816gxomfdn3f4.png)
here we know that both moving charges are of same sing in same directions
so magnetic field at mid point between them is given as
![B = (\mu_o q)/(4\pi r^2)(v_1 - v_2)](https://img.qammunity.org/2020/formulas/physics/high-school/e49lf4in4y21caylo7elyozuskm2i53fcs.png)
here we know that
![(\mu_0)/(4\pi) = 10^(-7)](https://img.qammunity.org/2020/formulas/physics/high-school/aok4zij60horlv4oq1nqn1qx7m2e3k2btg.png)
![r = 5 mm](https://img.qammunity.org/2020/formulas/physics/high-school/rpdurz6tcms8807c952q1ogfhr6qel4kwo.png)
![v_1 = 6.8 * 10^3 m/s](https://img.qammunity.org/2020/formulas/physics/high-school/1je79t8er6scsesyp51uk9qtkfm3ilv29c.png)
![v_2 = 2.9 * 10^3 m/s](https://img.qammunity.org/2020/formulas/physics/high-school/xmosle8jz3v4mr51uk0d861cbys7ra7rq0.png)
now we have
![B = (10^(-7) (1.6 * 10^(-19)))/((5 * 10^(-3))^2)(6.8 * 10^3 - 2.9 * 10^3)](https://img.qammunity.org/2020/formulas/physics/high-school/ekjxaia4xazgs3j92nx7jib1qyl033xbyh.png)
![B = 2.5 * 10^(-18) T](https://img.qammunity.org/2020/formulas/physics/high-school/m5chuynb99x8vbb7b8l28uk3vvgprevvqe.png)