In many instances, different engineering fields overlap. A good example is the manipulating arm of a robotic device.
The arm itself is made out of various materials, has joints, mechanisms for movement, sensors, etc. Mechanical engineers primarily design most of these items. However, the sensors, and to some extent the materials used, are also of interest to electrical engineers. In addition, the electrical engineer is interested in all of the electronics that control the robotic arm, including any microprocessors. The electrical engineer, or a computer engineer, may have written the software that controls the motion of the arm.Another set of overlapping activities occur between electrical engineering and physics. In the integrated circuits/microelectronics industry, both often work side-by-side on the same type of job.
This kind of overlap between disciplines should not be surprising. After all, computer engineering came from electrical engineering quite recently. Likewise, engineering as a whole developed from the principles discovered by scientists who would today be called physicists.