Final answer:
The net electric field at point A is directed towards the larger charge q2. To find the magnitude of the electric field at point B, one should calculate the individual electric fields and then vectorially combine them. The magnitude of the electric force on a proton at A is found using the net electric field and the charge of the proton.
Step-by-step explanation:
To solve the problems involving electric fields and forces due to point charges, we need to apply the principles of Coulomb's Law and the concept of the electric field. Coulomb's Law describes the force between two point charges, while the electric field describes the force a charge would experience due to other charges in its surroundings.
Direction of the Net Electric Field at Point A
For part (a), the direction of the net electric field at point A will be away from the positive charge q1 (6.15nC) and toward the larger positive charge q2 (12.0nC). Since q2 is larger, the net electric field at A will be in the direction of q2.
Magnitude of the Net Electric Field at Point B
Part (b) requires the calculation of the magnitude of the net electric field at point B. This is done by calculating the individual electric fields due to each charge at point B and then combining them vectorially, considering both magnitude and direction. The charges will exert forces in opposite directions at point B because they are both positive.
Magnitude of Electric Force on a Proton at A
For part (c), the magnitude of the electric force on a proton at A can be found using Coulomb’s Law, with the net electric field calculated in part (a) and the charge of a proton.