Answer
The magnitude of the magnetic field is $0.78~T$
Work Step by Step
We can find the magnitude of the magnetic field:
$F = q~v\times B$
$B = \frac{F}{q~v}$
$B = \frac{1.0 \times 10^{-13}~N}{(-1.6\times 10^{-19}~C)(8.0\times 10^5~m/s)}$
$F = -0.78~T$
The magnitude of the magnetic field is $0.78~T$.
