# Magnetic effect on AC circuits?

We know that when currents in two wires move parallel to each other, they attract each other and if they are moving anti-parallel to each other, they repel each other but we cannot observe this in our daily routine; why?

I know this experiment is based on DC circuit and we cannot observe this in electric transmission lines because in our homes we usually use AC.

But what is the actual reason behind that we cannot observe an attractive or repulsive force in daily circuits? If actually it is because of AC currents, then why does AC current not show magnetic effect?

• According to this, one can calculate: the force per unit length of a cable carrying $20A$ with $1cm$ appart, is $8$ milinewtons/meter. Not that great.... Nov 15 '16 at 15:30
• @Physicist137 Yes, but if you have e.g. a coil of wire in a transformer, the wires are under a millimeter apart, the field is significantly magnified by the ferromagnetic core, and you have many coils acting. The coils won't move, because they're glued in place, but they do 'breathe' as the current oscillates, and this is what causes the hum of a transformer at 50-60 Hz. Nov 15 '16 at 19:08
• (ahem, scratch that: at 100-120 Hz, since the direction of the current doesn't matter, or most probably one of its harmonics, at 400-480 Hz, which is deeper in the human hearing range.) Nov 15 '16 at 21:43
• You’ve never seen speaker wires jerk due to EMF? Nov 15 '16 at 23:06

Usually, conductors run in pairs, with a fixed distance (insulator) between them. Such a configuration prevents you from noticing the force between them. Note also that the force is not large - $2\times 10^{-7}~\rm{N}$ for two wires that are 1 m apart and carrying 1 A of current. Which makes it hard to notice unless the currents are very large, or you set up a sensitive experiment.