1m. They are unlike charges. So the force will be attractive. Force experienced by the charge q due to q is given by ) × −× =− (Using = i ) The charge q will experience an attractive force towards q which is in the negative x direction.
According to Newton’s third law, the force experienced by the charge q due to q is =− . Therefore, − N The directions of and are shown in the figure (case (b)). (c) If these two charges are kept inside the water, then the force experienced by q due to q q q W π e since e = e r e o we have q q W π e e e 12th - 12th - - - - - Unit Electrostatics tan θ = F mg e ( ) Since they are equally charged, the magnitude of the electrostatic force is k q e = where k = π e Here r = a = L sinθ. By substituting these values in equation ( ), tan sin θ θ k mg L ( ) Rearranging the equation ( ) to get q L mg k = sin tan θ θ = × sin tan q = .
× – C = . nC EXAMPLE . Calculate the electrostatic force and gravitational force between the proton and the electron in a hydrogen atom. They are separated by a distance of .
× – m. The magnitude of charges on the electron and proton are . × – C. Mass of the electron is m e = .
× – kg and mass of proton is m p = . × – kg. Solution The proton and the electron attract each other. The magnitude of the electrostatic