The magnitude of the force that acts on a charge of -7.9C at this spot is 2.21 x 10⁶ N.
Step-by-step explanation:
Electric field is the ratio of force and charge.
Electric field, E = 280000 N/C
Charge, q = -7.9 C
We have

The magnitude of the force that acts on a charge of -7.9C at this spot is 2.21 x 10⁶ N.