The emf induced in a moving conductor primarily depends on which factor?

The induced electromotive force (emf) in a moving conductor is primarily influenced by the speed of the conductor as it moves through a magnetic field. According to Faraday's law of electromagnetic induction, the induced emf is proportional to the rate of change of magnetic flux, which is directly related to how quickly the conductor moves through the magnetic field. The faster the conductor moves, the greater the change in magnetic flux experienced by the conductor per unit of time, resulting in a higher induced emf.

While the resistance of the conductor and the material can have effects on the overall current that flows due to the induced emf, they do not directly affect the amount of emf produced. The length of the conductor does play a role since a longer conductor in the same magnetic field may induce more emf due to having more area exposed to the magnetic field lines. However, the most significant factor in determining the magnitude of the induced emf is the speed of the moving conductor itself. Thus, the correct answer to the question is the speed of the moving conductor.