Potential due to a positive charge

For a positive point charge $q$, the electric potential at a point is $V = \frac{kq}{r}$ where $r>0$.

Since $q>0$ and $r>0$, we always have $V>0.$

Net potential due to a group of positive charges

If all charges are positive, then the total potential at any finite point is $V_{\text{net}} = \sum_i \frac{kq_i}{r_i}.$

Every term in this sum is positive, so their sum cannot be zero: $V_{\text{net}} > 0.$

Hence, net potential cannot be zero at any finite point.

Can the net electric field be zero?

Yes. Electric field is a vector quantity, so fields due to different positive charges can cancel each other.

For example, for two equal positive charges placed symmetrically, at the midpoint the field due to one charge is equal in magnitude and opposite in direction to the field due to the other. Thus, $\vec E_{\text{net}} = 0.$

But the potential there is $V_{\text{net}} = \frac{kq}{r} + \frac{kq}{r} > 0,$ so it is not zero.

Check options

• A: Net potential cannot be zero, but net electric field can be zero. ✅ Correct
• B: Says potential can be zero. ❌ False
• C: Says electric field cannot be zero. ❌ False
• D: Says both can be zero. ❌ False

Conclusion

The correct option is A.