if the force vector F elect A-->B is in the positive direction form the unit vector r A-->B , the unit vector must be multiplied by a negative number . where does this negative number come from in the Coulomb equation? Does this negative number indicate a repulsive force or an attractive force?
In the Coulomb equation, the negative sign arises from the nature of the electrostatic force between charged particles. The equation is given by:
F = k * (q1 * q2) / r^2
where F is the force, k is the Coulomb constant, q1 and q2 are the magnitudes of the charges, and r is the distance between the charges.
The negative sign in this equation is essential because it indicates the attractive or repulsive nature of the force. The force between two charges can either be attractive (opposite charges) or repulsive (like charges).
If the charges are of opposite sign (one positive and one negative), then the force will be attractive, and the negative sign in the equation ensures that the force vector points toward each other.
On the other hand, if the charges have the same sign (both positive or both negative), then the force will be repulsive. The negative sign in the equation indicates this repulsive nature and ensures that the force vector points away from each other.
Therefore, the negative sign in the Coulomb equation signifies the nature (attractive or repulsive) of the electrostatic force between charges.