The electric gun assembly consists of six parts i.e. an indirectly heated cathode, a control, grid surrounding the cathode, a focusing anode and an accelerating anode and a pre accelerating anode. And the focusing anode is located between preaccelerating and accelerating anode. The pre accelerating anode and accelerating anode are at the higher potential than the focusing anode therefore, these anodes create an electric field between them and act as a lens with a focus on the screen