Download Series Circuits

Series Circuits
A series circuit is a circuit where there is only one path from the source through all of
the loads and back to the source. This means that all of the current in the circuit
must flow through all of the loads.
One example of a series circuit is a string
of old Christmas lights. There is only one
path for the current to flow. Opening or
breaking a series circuit such as this at any
point in its path causes the entire circuit
to "open" or stop operating. That's because
the basic requirement for the circuit to
operate a continuous, closed loop path is
no longer met. This is the main disadvantage of a series circuit. If any one of the light
bulbs or loads burns out or is removed, the entire circuit stops operating. Many of
today's circuits are actually a combination of elements in series and parallel to
minimize the inconvenience of a pure series circuit.
Let's take a closer look at how a series circuit operates and the way resistance affects
the current flow.
Consider a simple series circuit consisting of a 120 volt outlet as the source, a switch,
and a 60 watt light bulb. When the switch is
open, the light cannot operate since the
circuit is not complete. There isno closedloop path for the current to flow through the
circuit. When the switch is closed, the light
bulb operates since the current flows through
the circuit. The bulb glows at its full
brightness since it receives its full 120 volts
and has the design current flow (Figure 1).
If two light bulbs are connected to the circuit
in series, the resistance of the circuit
doubles (Figure 2). The current flow is now
half of what it was when only one lamp was in the circuit as before. The voltage
across each lamp is now 60 volts due to the reduced current flow. Each bulb is
operating at only one-half its intended voltage, which will reduce its brightness. Since
each bulb is the same size, they each see equal voltage drop.
If we add a third 60-watt bulb to the
circuit, then each bulb will receive a
third of the total circuit voltage, or 40
volts (Figure 3). Each bulb will
produce even less light than before
because we continue to add more
resistance to the circuit each time we
add a bulb.
To further demonstrate how changing
resistance in series affects current
flow and voltage across each bulb, let's replace the third bulb with a 10-watt bulb
(Figure 4). What will happen?
The 10-watt bulb will glow
brightly but the other two
will barely produce light.The
10-watt bulb has such a large
resistance compared to the
other two 60-watt bulbs that
the 10-watt bulb gets the
highest percentage of the
voltage. The position of the
bulbs in the circuit does not
matter. It's the resistances
that determines how much voltage each of the bulbs will ultimately receive. In this
arrangement, the 10-watt bulb receives 110 volts, and each of the 60-watt bulbs is
receiving 5 volts. The 5 volts received by the 60-watt bulbs makes them barely glow,
while the 110 volts received by the 10-watt bulb makes it glow at close to, but not all
of, its full, intended brightness."
Resistance
Inductance
Capacitance
Combinations