Final answer:
Current in a copper wire within a magnetic field can be generated when there is relative movement between the wire and the magnetic field, in accordance with Faraday's Law of Electromagnetic Induction.
Step-by-step explanation:
Current can only be generated in the copper wire when the wire is moving relative to the magnetic field. This phenomenon is outlined by Faraday's Law of Electromagnetic Induction, which states that a voltage (and consequently a current if the circuit is closed) is induced in a conductor when it is exposed to a changing magnetic field. This can be achieved, for example, by moving the wire within the magnetic field or by altering the magnetic field itself.
An important element of this is the relative motion between the conductor and the magnetic field. Simply placing a wire in a static magnetic field with no relative motion will not induce a current. Replacing the wire with a non-metal wire or reversing the poles of the magnet without movement will also not induce a current. A more powerful magnet without relative motion will not make a difference either, as it is the change in the magnetic flux through the wire loop that induces the current.
The first demonstration of this principle involves moving a bar magnet through or away from a coil of wire, which changes the amount of magnetic field passing through the coil and generates a current. The same result is observed if the coil is moved around a stationary magnet. The direction of the induced current depends on the direction of the movement and can be determined with Lenz's Law, which states that the induced current flows in such a direction that it opposes the change in magnetic flux that produced it.