Most studies on the magnetic Aharonov–Bohm (A–B) effect focus on the action exerted by the magnetic flux on the electron beam, but neglect the back-action exerted by the electron beam on the magnetic flux. This paper focuses on the latter, which is the electromotive force ΔU across the solenoid induced by the time-dependent magnetic field of the electron beam. Based on the backaction analysis, we observe that the magnetic A–B effect arises owing to the interaction energy between the magnetic field of the electron beam and the magnetic field of the solenoid. We also demonstrate that the interpretation attributing the magnetic A–B effect to the vector potential violates the uncertainty principle.