A closely wound circular coil with radius 290 centimeter

Question

A closely wound, circular coil with radius 2.90 centimeter has 780 turns.

Part A: Find what must the current in the coil be if the magnetic field at the center of the coil is 6.00 × 10² T?

Part B: Find at what distance from the center of the coil, on the axis of the coil, is the magnetic field half its value at the center?