Explanation

The right-hand thumb rule gives the direction of the magnetic field around a straight current-carrying conductor: if the right thumb points along the current, the curled fingers show the field's direction. Fleming's left-hand rule gives the force on a current-carrying conductor (the motor rule), Fleming's right-hand rule gives the induced EMF (the generator rule), and Hund's rule concerns the filling of electron orbitals. It follows from applying the Biot-Savart law to a long straight wire.