Two coils are mounted, one a small distance above the other, with their planes parallel and axes along the same line. In one of them (the primary), an alternating current with sinusoidal waveform is supplied by an electric oscillator. At what times in the periodic current cycle is the induced end in the other coil ( the secondary) biggest in magnitude?
1. When the current in the primary coil is passing through zero.
2. When the current in the primary coil is at a maximum in one direction or the other.
3. Halfway in time between the instants when the primary current is zero and when it is maximum.
4. All times except when the primary is reversing direction.
5. All times except when the primary current has just reached its maximum in either directions and is about to start diminishing.