The AC Generator | Physics for GCSE/IGCSE - Year 11 PDF Download

Simple A.C Generators

• The generator effect can be utilized to produce alternating current (AC) in an alternator.
• A basic alternator is a specific type of generator that transforms mechanical energy into electrical energy in the form of alternating current. 

• When a rectangular coil rotates within a uniform magnetic field, it causes the pointer of the meter to initially deflect in one direction, then in the opposite direction, and then back again.
• This phenomenon occurs due to the coil cutting through magnetic field lines, inducing an EMF and consequently a current in the circuit.
• The pointer deflects in both directions because the current within the circuit undergoes repeated changes in direction as the coil spins.
• The reason behind this directional variation lies in the alternating direction of the induced EMF within the coil.
• As long as the coil maintains its rotational motion in the same direction, this alternating pattern of induced EMF and current persists.

Graphs for A.C. Generators

• When an A.C. generator is in action, it produces an alternating current that varies in both size and direction as the coil within it rotates. 
• The magnitude of the induced electromotive force (EMF) generated by the coil is directly correlated to the number of magnetic field lines it intersects.

• At points where the coil experiences a maximum number of field lines passing through it, the induced electromotive force (e.m.f.) reaches a minimum level.
• Conversely, when the coil encounters a minimum number of field lines passing through it, the induced e.m.f. attains its maximum value.
• Positions 1 and 3 in the diagram represent instances where the coil intersects the maximum number of field lines, resulting in zero induced e.m.f. at these points.
• In contrast, positions 2 and 4 denote situations where no field lines traverse through the center of the coil, leading to maximum induced e.m.f.