The Direction of the Induced Current in a Generator – GCSE Physics (Triple) WJEC Revision

Understanding the direction of the induced current in a generator begins with knowing about electromagnetic induction. This is a process by which a conductor moving in a magnetic field induces a voltage.
The direction of the induced current in a generator is governed by Fleming’s right-hand rule. This states that if your thumb points in the direction of movement of the conductor (or in generators, the direction the coil is rotating), and your first finger points in the direction of the magnetic field, then the induced current will flow in the direction that your second finger points to.
The direction of the magnetic field in basic generators moves from the North pole of the magnet to the South.
The direction of rotation in a simple, hand-crank generator is typically determined by the user. However, in mechanical generators (like in turbines), the direction depends on the mechanical force being applied.
The direction of the induced current changes each half cycle in a generator. This is because the side of the loop that moves up initially becomes the side that moves down in the next half cycle.
Therefore, the induced current in a generator is alternating current (AC) as its direction changes regularly, following the change in the direction that the coil cuts through the magnetic field.
The amplitude of the induced current depends on the speed of rotation, the strength of the magnetic field and the number of turns in the coil. However, the direction purely depends on Fleming’s right-hand rule.
It is important to understand that reversing either the direction of the magnetic field, or the direction of the movement, will result in the reversal of the direction of the induced current.
During each rotation, when the plane of the coil is parallel to the magnetic field lines, no voltage is induced. However, a voltage is induced to its maximum when the plane of the coil is perpendicular to the magnetic field lines. This changing amplitude can be represented using a sine wave.
Diagrams or models of generators often show a split-ring commutator, which is a device used to switch the direction of current in a coil every half cycle. This allows the output to be direct current (DC) instead of alternating current (AC) because it maintains the direction of the current flow outside the generator.
In conclusion, the direction of the induced current in a generator is dependent on the direction of the rotation and the magnetic field but can be manipulated using components like a commutator.