In the present research note, we have derived the explicit expression for the perihelion precession and the deflection angle of light by the gravitational object. The explicit expression for the trajectory of the planet orbiting around a central object in the framework of Newtonian theory as well as general relativity has been discussed. It is studied the deflection of the light ray and gravitational lensing effects by the gravitational object in the weak field approximation. Using the gravitational lensing equation the magnification of the primary and secondary images has been derived. It is shown that for small angle β, it is difficult to distinguish the magnifications of the primary and secondary images, while for the largest value of the angle β the magnification of the primary image dominates will equal to the total magnification. The time delay of the light ray passing through the gravitational object is also discussed. Finally, the classical expression for the energy of relativistic particles has been derived in the frame of general relativity.