A long horizontal wire P Q of mass m and carrying a steady current i₁ is free to move in the vertical plane. It is in equilibrium at a height d above another horizontal long wire R S of mass m and carrying a current i₂ . The wire R S is fixed and not free to move. Which of the following statements is/are correct?

Options

1. AThe magnetic force on the lower wire is in the vertically downward direction.
2. BThe magnitude of the magnetic force per unit length on the upper wire is ₀ i₁ i₂ 2 d
3. CIf the upper wire as a whole is displaced slightly upward, it will perform simple harmonic motion with time pe
4. DIf the current in the upper wire is reversed, the wire will no longer be in equilibrium.