Answer:
[tex]B = 2.5 \times 10^{-18} T[/tex]
Explanation:
Magnetic field due to moving electron is given by the formula
[tex]B = \frac{\mu_0 qv}{4\pi r^2}[/tex]
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
[tex]B = \frac{\mu_o q}{4\pi r^2}(v_1 - v_2)[/tex]
here we know that
[tex]\frac{\mu_0}{4\pi} = 10^{-7}[/tex]
[tex]r = 5 mm[/tex]
[tex]v_1 = 6.8 \times 10^3 m/s[/tex]
[tex]v_2 = 2.9 \times 10^3 m/s[/tex]
now we have
[tex]B = \frac{10^{-7} (1.6 \times 10^{-19})}{(5 \times 10^{-3})^2}(6.8 \times 10^3 - 2.9 \times 10^3)[/tex]
[tex]B = 2.5 \times 10^{-18} T[/tex]