Explanation:
Electric field is the ratio of force and charge.
Electric field, E = 280000 N/C
Charge, q = -7.9 C
We have
[tex]E=\frac{F}{q}\\\\280000=\frac{F}{7.9}\\\\F=280000\times 7.9\\\\F=2.21\times 10^6N[/tex]
The magnitude of the force that acts on a charge of -7.9C at this spot is 2.21 x 10⁶ N.