3. History of Alternating Current
William Stanley,Jr. designed one of the first
practical devices to transfer AC power efficiently
between isolated circuits.
The AC power system used today developed
rapidly after 1886, and included contributions by
Nikola Tesla and Carl Wilhelm Siemens.
4. What Is Alternating Current?
• Alternating current electricity is the type of
electricity commonly used in home and
businesses throughout the world.
• AC electricity is created by an AC electric
generator , which determines the frequency.
• Some Ac wave froms are irregular or
complicated.
7. Alternating Current
• A sinusoidal ac waveform starts at zero
– Increases to a positive maximum
– Decreases to zero
– Changes polarity
– Increases to a negative maximum
– Returns to zero
• Variation is called a cycle
9. Advantages
• The single greatest advantage of alternating
current is that AC current can be transformed
and DC current cannot be transformed.
• It can be controlled by a wide range of
components eg , resistors , capacitors and
inductors.
• This allows high-voltage electrical power to be
distributed whit smaller wires and lower
amperage.
12. AC Circuits - Resistors
In an AC
resistor circuit,
Ohm’s law
applies to both
the
instantaneous
and peak
currents and
voltages.
13. A Capacitor In AC
• Capacitors react against a change in voltage by
either supplying current(discharging) or drawing
current(charging).
• In an AC circuit a capacitor alternates between
charging and discharging.
• As a resutl , capacitors behave in a similar way to
resistoirs in that they oppose the current in a
circuit as they charge and discharge.
