# Physical example of line charge

Electric field due to an infinite line charge, sheet of charge, point charge, etc are popular problems solved in most text on Gauss's law of electromagnetism.

My question: does an (exact or approximate) example of "infinite/finite line of charge" exist in the physical world?

While we find application of sheet of charge (though finite, not infinite) in case of capacitors, and i can imagine the physical presence of point charge and spherical charge, etc, but a line of charge with uniformly distributed charge density, which basically means a thin conductor with charge Q per unit length - can we have such a thing?

As i understand:

1. If we connect a battery to a straight wire, with circuit closed, we get a current, but still, any section of the wire is charge-less. So, not an example of line charge.

2. If we connect a battery to a wire, with circuit not closed, the charges inside the conductor will move within so as to cancel the applied electric field. So again the conductor won't have uniform charge, so not an example of line charge.

3. If we connect ac voltage to a wire, we get sinusoidal charge variation along the wire, so, again not an example.

Can anyone please give a realistic example, which can come close to a line of uniform charge.