When the key is closed, the conductor AP will deviate from its initial position

Solution:

When the key is closed, current flows through the conductor. This conductor is placed within the magnetic field of the horseshoe magnet. A current-carrying conductor in a magnetic field experiences a force (Lorentz force). This force will cause the conductor to deviate from its initial position. The direction of deviation depends on the direction of the current and the direction of the magnetic field, as described by Fleming's left-hand rule.

Answer: When the key is closed, the conductor AP will deviate from its initial position due to the magnetic force acting on it.