You
will also able to answer what is alternating current electricity, how
AC differs from DC, the Benefits of AC, and what is power factor.
Definitions
· Alternating Current (AC) is that type of electrical current, which changes
or reverses the direction of the flow of electrons at regular and equal
intervals of time.
· Alternating current, or AC, is the type of
electricity that reverses the direction of its flow many times per second.
· Alternating
current is any current that varies in magnitude and direction at regular
intervals of time.
What is Alternating
Current (AC) Electricity?
An alternating current
of electricity has the important characteristics of changing polarity and
reversing direction at regular intervals. AC current changes direction about
120 or 100 times each second, resulting in a waveform that looks similar to
that of the traditional sound wave; this visual analogy led to the wave being
called an alternating current wave, or simply an AC wave. AC power sources are
one of the two most common types used to provide electricity to consumers in
North America, with many millions of households using this type of power supply
in their everyday lives.
Alternating Current
An alternating current
can be defined as a current that changes magnitude and polarity periodically.
It can also be defined as a current that repeatedly changes or reverses
direction, as opposed to a direct current, which always flows in a single
direction. Alternating current is abbreviated as AC, the current flowing in power
lines, and normal household electricity that comes from a power station or
substation is alternating current. Some important terms to understand AC are,
Waveform
A representation
of how alternating current (AC) varies with time is called Waveform. There are many types of
waveforms but the most familiar AC waveform is the sine wave.
Cycle
One
complete wave of alternating current or voltage is called a cycle.
Alternation
One-half
of a cycle is called alternan or alternation. Either the positive or negative half cycle is
considered an alternation.
Period
The
time required to produce one complete cycle of a waveform is called a period or
time period.
Frequency
The
number of cycles per second time is called a frequency. It is the reciprocal of
the time period and its unit is hertz, represented by Hz. The standard
frequency value in the US is 60 Hz, while in the UK, Asia, and other parts of
the world its standard value is 50 Hz.
From the graph, we can
see the waveform of the alternating current. In the waveform, the charged
particles tend to start moving from zero increase to a maximum, and start
decreasing back to zero completing one positive cycle. The particles then
reverse the direction and start increasing to reach the maximum in the opposite
direction. After reaching to negative maximum AC again moves towards zero and
returns to the original value, hence completing a negative cycle. The cycle is
repeated the same way, again and again.
The properties of an
alternating current.
With direct current, the
voltage is always constant, and the current flows in a certain direction. In
contrast, the voltage of alternating current is cyclically from positive to
negative and from negative to positive, so the direction of the current also changes
periodically. With direct current, the voltage is always constant, and the
current flows in a certain direction. In contrast, the voltage of alternating
current is cyclically from positive to negative and from negative to positive,
so the direction of the current also changes periodically.
Generation of
Alternating Current AC
As we all know,
alternating current is produced by a generator. The generator consists of
magnets and coils that rotate in a magnetic field. When a wire is rotated in a
magnetic field, the change in the strength of the magnetic field induces a
force in the wire, which drives the electric charge around the wire. This force
initially drives the charge in a specific direction along the wire. Then when
the ring is rotated 180 degrees, the force is reversed, causing the current to
flow in the opposite direction of the wire. Every 180 degrees of rotation of
the loop, the direction of the force changes, and the polarity of the current
changes accordingly.
One advantage of AC
power is that it is relatively inexpensive to change the supply voltage. In
addition, the unavoidable energy loss during long-distance transmission is much
lower using alternating current than direct current.
An analogy
The first thing to
understand about AC current is that it's not a form of electricity, but rather
a way of delivering electricity. The second thing to know is that it's not the
same as DC current. Think of alternating current as water moving through a
pipe, says Dr. John Poulos, professor at Purdue University in West Lafayette,
Ind., and author of Circuit Analysis with DC and AC Theory.
In an AC circuit the
voltage oscillates back and forth between positive and negative values, he
says.
How AC differs from DC
Alternating current (AC)
electricity, as the name suggests, alternates its direction of flow. Whereas
Direct current (DC) flows only in one direction. This means that a power
company can use AC electricity to transmit power over long distances without
worrying about voltage drop-off. DC electricity would need more power stations
closer to each other to do the same job.
The benefits of AC over
DC
Many things about AC and
DC electricity are different, but the most important difference for this
section is that alternating current takes more time to travel a given distance
than direct current. As a result, in an AC system, the voltage will vary as
electricity travels from point A to point B. It becomes important to
distinguish between phases of an AC wave since each phase behaves differently.
Alternating Current
Formula
The alternating current
formula is a mathematical equation for calculating the alternating current or
AC. The formula for calculating AC power is,
P = V I Cos ɸ
Where
P is the alternating power, V is the alternating voltage, I is the alternating
current and Cos ɸ is the power factor.
Power
Factor
The
cosine of the phase difference between voltage and current is called power
factor and is measured by using the formula Power Factor = Cos ɸ, where ɸ is the phase difference between the
voltage and current phasor. The ideal value of the power factor is unity or it
should be equal to 1.
Examples in your daily
life
1. The lights in your
home are powered by an alternating
2. It's a type of
alternating current electricity that runs at the speed of 60 or 50 hertz, and
it has many advantages over direct current
3. AC power travels more
efficiently over long distances than DC power
4. Your laptop charger,
TV remote, and cell phone charger all use AC power
5. For your
computer to work properly with an alternating current, you'll need an adapter
6. The advantage of AC
power is that it can handle heavy loads better than DC power
7. Direct current flows
in one direction only.
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