Alternators, Dynamos & Microphones [Physics only, Higher Tier]

Generators

• The generator effect is used in an alternator to generate alternating current (ac) and in a dynamo to generate direct current (dc)
• In both, a coil is rotated in a magnetic field (or a magnet is rotated inside a coil). The sides of the coil cut the field lines, so a potential difference is induced across the coil
• As the coil turns, each side moves up through the field for half a turn and down for the other half, so the induced potential difference reverses every half turn
• The induced potential difference is largest when the coil is horizontal (the sides are cutting field lines fastest) and zero when the coil is vertical (the sides are moving parallel to the field, not cutting it)