Question

Why does a compass needle show deflection when brought near a current carrying conductors?

Answer 1

due to magnetic force exerted by current carrying conductor
it is according to bio savort law
b=ki lsin(theta)/r^2

Answer 2

When compass is brought near a bar magnet, its magnetic field lines interact with that of the bar magnet. Hence, a compass needle shows a deflection when brought near the bar magnet.

Hope it helps....