Answer:
B= 916.7ηT or 916.7 × 10^-9 or 0.0000009167
Explanation:
Magnetic field due to a current carrying conductor is given by
B= μI/(2πr)
B: magnetic field
μ: permeability of free space
r: perpendicular distance from the wire
For r= 0.25, B = 0.00000275
0.00000275= μI/(2π×0.25)
μI/(2π) = 0.0000006875
For r= 0.75
B= μI/(2πr)
B= 0.0000006875/0.75
B= 916.7ηT or 916.7 × 10^-9 or 0.0000009167