In the given graph shown the variation of the potential energy U by the interaction between two particles, with the distance separating them, r.

(i) C is a point of stable equilibrium.
(ii) B and D equilibrium points
(iii) The force of interaction between the particles is repulsive between points C and A.
(iv) The force of interaction between the two particles is attractive between points Cand B, and repulsive between D and E on the curve Choose correct statement(s) ?

Options

A. (ii) and (iv)
B. (ii) and (iii)
C. (i) and (iii)
D. (i) and (iv)

Answer

C

Explanation

Force acting on the particle is given by, `F = -(dU)/(dr)` = -(slope of U - r graph)
If the slope of the graph is positive then the force of attraction will act and for the negative slope, the force repulsion will act.
At point C, `F = -(dU)/(dr) =0`, hence it is a point of stable equilibrium.
Also, from C to A, the slope is negative, i.e., the repulsive force will act between two particles.