Question

what happens to comet tail when it goes farther away from sun

Answer 1

The formation of the tail stoops and the heat of the solar wind gets reduced.

Answer 2

The tail of the comet is gas and dust boiled off by the heat if the sun. So no new tail material is emitted once it gets away from the sun. The material emitted near the sun goes into its own orbit, similar to but not the same as the comet. So if the Earth passes through the comet’s orbit we can expect an increase in meteors from the dust component.