To find the required coil current for a toroidal core with 1000 turns and a total flux of 0.0002 Wb, first calculate the magnetic field strength (B) using the formula B = Flux / area. The area can be determined based on the core's dimensions, with an outer radius of 6 cm and an inner radius of 1 cm. Next, reference the B-H curve for the non-magnetic core material to find the magnetic field intensity (H). Finally, use the relationship H = NI to solve for the current (I) needed, given the number of turns (N). This method effectively determines the necessary coil current for the specified magnetic circuit.