Two identical, closely wound, circular coils, each having selfinductance L, are placed next to each other, so that they are coaxial and almost touching. If they are connected in series, what is the selfinductance of the combination? What if they are connected in parallel? Can they be connected so that the total inductance is zero? Explain

Two identical, closely wound, circular coils, each having selfinductance L, are placed next to each other, so that they are coaxial and almost touching. If they are connected in series, what is the selfinductance of the combination? What if they are connected in parallel? Can they be connected so that the total inductance is zero? Explain