Answer:
Electric field, E = 2.22 V/cm
Step-by-step explanation:
Given that,
The distance between 7 V equipotential and 5 V at point B is 0.9 cm. The relation between electric field and electric potential is given by :
![E=(\Delta V)/(d)](https://img.qammunity.org/2020/formulas/physics/college/erk3uhtlpimvz9sswhv3ak1rr5iy3nb2mz.png)
![E=(7\ V-5\ V)/(0.9\ cm)](https://img.qammunity.org/2020/formulas/physics/college/ti20tqe9ckry60e8uqktg1din467rni8vw.png)
E = 2.22 V/cm
So, the magnitude of the electric field at point B is 2.22 V/cm. Hence, this is the required solution.