NOVELTY - The apparatus has a carrier (5) i.e. drill string (6), conveyed through a borehole (2). An electrical circuit charges energy storage devices and discharges one of the energy storage devices to a switchable-magnet and other energy storage devices to another switchable-magnet, where change in a first magnetic field caused by discharging of the former energy storage device and change in a second magnetic field caused by discharging of the latter energy storage device induce currents in a formation (4) to generate signals to estimate a property of the formation.    USE - Apparatus for estimating an electrical property e.g. resistivity and conductivity (all claimed), of an earth formation penetrated by a borehole to facilitate hydrocarbon production, geothermal production and carbon dioxide sequestration. Can also be used for estimating material composition or boundaries of the formation.    ADVANTAGE - The apparatus facilitates deep probing of up to 100 feet or more into the formation using magnetic dipole reversals to induce formation currents such that the capacitors can provide enough energy to switchable magnet coils to generate changing magnetic fields, so that the electrical property of the formation can be determined up to 100 feet or more ahead of a drill bit while the borehole is being drilled by improving induction of logging tools to perform measurements in a quick manner. The capacitors for the switchable magnets allow the magnetic dipole reversals to be closely spaced in time, thus reducing errors introduced by tool rotation in the measurements while enhancing while-drilling measurements rapidly when charging of the capacitors is performed during relatively long gaps between measurement sets.    DETAILED DESCRIPTION - The drill string is a logging-while-drilling or measurement-while-drilling string. The energy storage devices are capacitors. INDEPENDENT CLAIMS are also included for the following:    (1) a method for estimating a property of an earth formation penetrated by a borehole    (2) a non-transitory computer-readable medium comprising a set of instructions for estimating a property of an earth formation penetrated by a borehole.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of an induction logging tool placed in a borehole penetrating an earth formation.    Borehole (2)    Formation (4)    Carrier (5)    Drill string (6)    Drilling rig (8)