Example 7 Figure a and b show the field lines of a positive

Last updated: 6/6/2023

Example 7 Figure a and b show the field lines of a positive and negative point charge respectively m c d a b a Give the signs of the potential difference Vp Vai VB VA b Give the sign of the potential energy difference if a small negative charge is moved from points Q to P from point A to B Give the sign of the work done by the field in moving a small positive charge from Q to P Give the sign of the work done by the external agency in moving a small negative charge from B to A e B 1 e Does the kinetic energy of a small negative charge increase or decrease in going from B to A a As Vx Thus Vp Vo Thus Vp Vo is positive Also V is less negative than VA VB VA or VB VA is positive b A small negative charge will be attracted towards positive charge The negative charge moves from higher potential energy to lower potential energy Therefore the sign of potential energy difference from Q to P is negative Similarly PE PE and hence sign of potential energy differences is negative c In moving a small positive charge from Q to P work has to be done by an external agen against the electric field Therefore work done by the field is negative d In moving a small negative charge from B to A work has to be done by the external agen It is positive Due to force of repulsion on the negative charge velocity decreases and hence the kin