Final answer:
Decreasing the speed of a magnet moving relative to a coil results in a C. lower induced current because it decreases the rate at which the magnetic flux through the coil changes, leading to a smaller induced emf and current.
Step-by-step explanation:
Decreasing the speed of a magnet moving relative to a coil reduces the induced current because it decreases the rate of change of the magnetic flux through the coil. According to Faraday's Law of Electromagnetic Induction, the induced electromotive force (emf) in a circuit is directly proportional to the rate of change of the magnetic flux through the circuit. When the magnet moves more slowly, the magnetic flux changes less rapidly, resulting in a smaller induced emf and therefore a smaller induced current. The correct answer to the question 'Why does decreasing the speed of the magnet reduce induced current?' is C) Lower speed decreases the rate of magnetic flux change.
The movement of the magnet generates an electrical current because it changes the number of magnetic field lines that intersect the coil, which is fundamentally related to the concept of magnetic flux. Quick movements lead to rapid changes, hence larger currents, while slower movements result in smaller changes and therefore smaller currents. None of the other options describes the physics accurately: Decreasing speed does not reduce the magnetic field strength (A), slower movement does not increase magnetic resistance (B), and slow motion does not enhance magnetic shielding (D).