Download Series and Parallel Circuits

Current and Voltage,
Series and Parallel
Having measured the current and voltage in series and
parallel circuits, I can design a circuit and show the
advantages of parallel circuits in everyday application- SCN
3-09a.
Today we are going to …
• Learn what the terms ‘current’, ‘voltage’ and
‘power’ represent
• Learn about the differences between series
and parallel circuits
And we will…
• Be able to build series and parallel circuits
• Be able to measure current and voltage in
series and parallel circuits.
We know that electricity is a form of
energy that helps make lots of useful
things work.
Electrical current is the term we use to describe
the movement
throughout a circuit.
of electrical charge
Let’s look at electrical charge a bit more…
Charge is a feature of matter.
It causes a force (a push or pull)
when placed near another charge.
Charges can be positive or negative.
Like charges repel
each other.
Opposite charges
attract each other.
If an object
gains
electrons it
becomes
negatively
charged
If an object
loses
electrons it
becomes
positively
charged
Electrical current (I) is defined as
how much charge (Q) is transferred
per second (s)
-The more charge that flows, the bigger the current-
Current = Charge/time
Q
I t
- Current is measured in
Amperes (A)
- Time is measured in
seconds (s)
- Charge is measured in
Coulombs (C)
A potential difference is needed
to allow an electrical charge to
flow through a component.
This difference in electrical energy between
two parts of a circuit is called the voltage.
Voltage is measured in…
Volts! (V)
Series Circuits
When components are
connected one after the
other in a continuous loop,
we say the circuit is
arranged in series (it has no
branches…)
Just like this!
Try experimenting with this now!
What happens when you unplug one bulb?
Parallel Circuits
When components are
connected on different
loops, we say the circuit is
arranged in parallel (This
variety of circuit has
branches…)
Like this one!
Try experimenting with this now!
What happens when you unplug one bulb?
Measuring the Current
in a Series Circuit
A
A
We
measure
current
using an
Ammeter.
We connect an ammeter
in series with the components
I2
A
A
I1
The current is
the same
everywhere in
the series circuit.
I1 = I2
Try experimenting with this now!
Your total current is determined by the number of cells.
We connect a voltmeter
in parallel with the components
V
The voltage is
shared
between all of
the
components in
the circuit.
Try experimenting with this
now!
A
I5
A
I2
I3
I4
A
A
A
I1
In a parallel circuit,
the total current is
distributed across
the components.
I1 and I5 are 0.3A
I2 = 01.A
I3 = 0.1A
I4 = 0.1A
V
V1
V2
V
V
V3
In a parallel circuit, the
voltage measured
across is each
component is the same
as the voltage of the
source.
V1 = 1.5V
V2= 1.5V
V3= 1.5V
What about
POWER?
Power (P) is a
measure of the rate
of energy transfer.
Power is measured
in Watts (W)
P
I V
Today we have…
• Learnt what electrical current is and how
charges behave
• Learnt the relationship between current, charge
and time.
• Learnt what voltage is
• Learnt how to measure voltage and current in
series and parallel circuits
• Learnt what power is
• Learnt how to calculate Power when we know the
current and the voltage