If a material is not present in a time-varying magnetic field, there will be no flux linkage and therefore no electromotive force (EMF) induced in that region. The induction of EMF occurs due to the change in magnetic flux linking a conductor or a circuit. According to Faraday's law of electromagnetic induction, an EMF is induced in a conductor when there is a change in the magnetic field threading through it.
The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux, given by the equation:
EMF = -dφ/dt
where EMF is the electromotive force, dφ/dt is the rate of change of magnetic flux, and the negative sign represents the direction of the induced current according to Lenz's law.
If there is no material present in the time-varying magnetic field, there is no conductor or circuit to experience a change in magnetic flux, and therefore no EMF will be induced.