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We have analyzed multi-wavelength observations and magnetic-field data forthe solar flare of May 10, 2012 (04:18 UT) and have detected a sign inversionof the signal in the line-of-sight magnetic measurements in the umbra of asmall spot. This effect is associated, at least partly, with the emergence of anew magnetic field. Almost at the same time, a burst of hard X-rays wasrecorded, and a wave in the vacuum ultraviolet (EUV) range (a "sunquake") wasgenerated due to the impact of the disturbance in the energy release range onthe photosphere. At the beginning of the event, a sigmoid flare was recorded,but it did not spread, as it usually does, along the polarity inversion(neutral) line. SDO/HMI full-vector measurements were used to extrapolate theAR 11476 magnetic field to the corona, and the distribution of verticalcurrents $j_z$ in the photosphere was obtained. The distribution of currents inthe active region shows that the relationship between them and the occurrenceof flares is very intricate. We have corroborated that the expected "ideal"behavior of the current system before and after the flare (e.g., see (Sharykinand Kosovichev, 2015)) is observed only in the sigmoid region. The resultsobtained were compared with the observations of two other flares recorded inthis AR on the same day, one of which was similar to the flare under discussionand the other was of different type. Our results confirm that the formation anderuption of large-scale magnetic flux ropes in sigmoid flares are associatedwith the shear motions in the photosphere and the emergence of twisted magnetictubes, as well as with the subsequent development of the torus instability.

Evidence of the Relationship between the Emerging Magnetic Fields, Electric Currents, and Solar Flares Observed on May 10, 2012