Two infinitely long parallel wires 5 cm apart in air carry currents of 2A and 4A respectively. Find the magnitude of the force on each metre of wire if currents are (i) in the same direction. (ii) in opposite direction.

Explanation

To solve the problem of finding the force per unit length between two infinitely long parallel wires carrying currents, we can use the formula for the magnetic force between two parallel currents.

### Given:
- Distance between the wires (r) = 5 cm = 0.05 m
- Current in wire 1 (I₁) = 2 A
- Current in wire 2 (I₂) = 4 A
- Permeability of free space (μ₀) = 4π × 10⁻⁷ Tm/A

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