Q.24. The gravitational force between a point like mass M and an infinitely long, thin rod of linear mass density $\lambda$ at a perpendicular distance L from M is
(1) $\frac{MG\lambda }{L}$
(2) $\frac{1}{2}$ $\frac{MG\lambda }{L}$
(3) $\frac{2MG\lambda }{L}$
(4) infinite.