Final answer:
The magnetic field at a point midway between two parallel wires carrying currents in the same direction can be found using Ampere's law. The magnetic field is calculated as (μ₀ * I₁ * I₂) / (2π * d), where μ₀ is the permeability of free space, I₁ and I₂ are the currents in the wires, and d is the distance between the wires. Plugging in the given values, the magnetic field is 0.024 T.
Step-by-step explanation:
The magnetic field at a point midway between two long parallel wires carrying currents in the same direction can be found using Ampere's law. The equation to calculate the magnetic field is B = (μ₀ * I₁ * I₂) / (2π * d), where B is the magnetic field, μ₀ is the permeability of free space, I₁, and I₂ are the currents in the two wires, and d is the distance between the wires.
Plugging in the given values: I₁ = 8.0 A, I₂ = 12 A, and d = 0.40 cm (0.004 m), we can calculate the magnetic field using B = (4π * 10^-7 T*m/A * 8.0 A * 12 A) / (2π * 0.004 m) = 0.024 T = 24 x 10^-2 T.
So, the magnetic field at a point midway between the two wires is 0.024 T (option b).