Practical 5Topic
: Electrical circuits
Purpose: To determine the advantages and disadvantages of series
and parallel circuits.
Theoretical
knowledge: An electronic circuit is composed of individual
electronic components, such as resistors, transistors, capacitors,
inductors and diodes, connected by conductive wires or traces
through which electrical current can flow. The combination of
components and wires allows various simple and complex operations
to be performed: signals can be amplified, computations can be
performed, and data can be moved from one place to another.
Circuits can be constructed of discrete components connected by
individual pieces of wire, but today it is much more common to
create interconnections by photolithographic techniques on a
laminated substrate (a printed circuit board or PCB) and solder the
components to these interconnections to create a finished circuit.
In an Integrated Circuit or IC, the components and interconnections
are formed on the same substrate, typically a semiconductor such as
silicon or (less commonly) gallium arsenide.
Breadboards, per boards or strip boards are common for testing
new designs. They allow the designer to make quick changes to the
circuit during development. An electronic circuit can usually be
categorized as an analog circuit, a digital circuit or a
mixed-signal circuit (a combination of analog circuits and digital
circuits).Components of an electrical circuit or electronic circuit
can be connected in many different ways. The two simplest of these
are called series and parallel and occur very frequently.
Components connected in series are connected along a single path,
so the same current flows through all of the components. Components
connected in parallel are connected so the same voltage is applied
to each component.A series circuit
Example of parallel circuit
A circuit composed solely of components connected in series is
known as a series circuit; likewise, one connected completely in
parallel is known as a parallel circuit.
In a series circuit, the current through each of the components
is the same, and the voltage across the components is the sum of
the voltages across each component. In a parallel circuit, the
voltage across each of the components is the same, and the total
current is the sum of the currents through each component.
As an example, consider a very simple circuit consisting of four
light bulbs and one 6V battery. If a wire joins the battery to one
bulb, to the next bulb, to the next bulb, to the next bulb, then
back to the battery, in one continuous loop, the bulbs are said to
be in series. If each bulb is wired to the battery in a separate
loop, the bulbs are said to be in parallel. If the four light bulbs
are connected in series, the same current flows through all of
them, and the voltage drop is 1.5V across each bulb and that may
not be sufficient to make them glow. If the light bulbs are
connected in parallel, the current flowing through the light bulbs
combine to form the current flowing in the battery, while the
voltage drop is 6.0V across each bulb and they all glow.
In a series circuit, every device must function for the circuit
to be complete. One bulb burning out in a series circuit breaks the
circuit. In parallel circuits, each light has its own circuit, so
all but one light could be burned out, and the last one will still
function.
Materials:
i. Battery holders
ii. Batteries
iii. Several insulated wires
iv. Ammeter
v. Voltmeter
vi. Light bulbs
Activity 1: Building a simple series and parallel circuits.
Procedures:
1. Both of the circuits shown below was constructed by using a
battery holder, a battery, several insulated wires and two light
bulbs for each circuits.
A series circuit
A parallel circuit2. All wires were connected and the light
bulbs were observed.
3. Now, the ammeter and voltmeter were connected in both the
above circuits. A suitable table was constructing to record the
readings.
4. Now, one bulb was unscrewed in each circuit. The remaining
bulbs was observed and also been recorded down the readings of both
the ammeter and voltmeter in each circuit. 5. Now, another bulb was
connected in series to circuit A. the remaining bulbs were observed
and the readings of both the ammeter and voltmeter were also
recorded down.
6. Now, another bulb was connected in parallel to circuit B. the
remaining bulbs were observed and the readings of both the ammeter
and voltmeter were also recorded down.
Result
:
Parallel circuitAmmeter (A)Voltmeter (V)
2 bulbs0.141
1 bulbs0.141
3 bulbs0.141
Series circuitAmmeter (A)Voltmeter (V)
2 bulbs0.131.3
1 bulbs0.140.8
3 bulbs0.120.4
Questions:
1. What happens to the bulbs in a series circuit if one of the
bulbs burns out? Explain.
If one of the bulbs was burn out, the other bulbs will be off or
shot down. This is because there is only one path of electrons in
the circuit. This meant that, the electric cannot flow through the
path because there was no conductor as a path. 2. What happens to
the bulbs in a parallel circuit if one of the bulbs burns out?
Explain.
If one of the bulbs was burn out, the other bulbs is still on.
This is because the electricity has another alternative path to
flow through in a parallel circuit. So, the other bulbs are still
on lighting.3. You are building a string of lights using several
bulbs. How is the brightness of the lights related to whether you
connect the bulbs in series or in parallel?In the series circuit,
we see that the bulbs were dimmer. This is because the electric or
the current which going through the bulbs are in smaller amount. It
is cause of the resistance in the bulb. In other words, the more
the bulbs in a circuit, the higher the resistance the circuit has.
So, the brightness of the bulbs is dimmer than the parallel
circuit. For the bulbs which connected in a parallel circuit, we
have seen that all of them receive full voltage result in
brightness. This meant that, all the bulbs have the same
brightness.
4. What happens to the bulbs in a series circuit if another bulb
is connected in series to it? Explain.
The bulbs become dimmer or less in brightness than before. This
is because by adding another bulb, it will increase the resistance
in the circuit. So, the more the bulbs the dimmest light it will
be. 5. What happens to the bulbs in a parallel circuit if another
bulb is connected in parallel to it? Explain.
The bulbs are still maintained the brightness or the light. This
is because they have got the same voltage which flow through them.
Activity 2: Building a combined series and parallel circuit.
Procedures:
1. The circuit shown below was constructed by using a battery
holder, a battery, a switch, several insulated wires and three
light bulbs.
A combined circuit 2. The switch was connected and the light
bulbs were observed.
3. Now, the ammeter and the voltmeter were connected to measure
the current and potential differences through each bulb. A suitable
table was constructed to record the readings.
4. Now, the bulb 1 was removed. The remaining bulbs were
observed and the readings of both the ammeter and voltmeter were
recorded down.
5. Now, the bulb 2 was removed. The remaining bulbs were
observed and the readings of both the ammeter and voltmeter were
recorded down. Result
:
Parallel circuitAmmeter (A)Voltmeter (V)
Bulbs 2,30.242.9
Series circuitAmmeter (A)Voltmeter (V)
Bulbs 1,30.202.9
Questions:
1. What happens to the other bulbs in the circuit when bulb 1 is
removed? Explain.The bulb 2 and 3 are off because bulb 1 is
unconnected from the circuit. As we can see, the bulb 1 was
connected at the series circuit in this experiment. So, when it is
unconnected from the series circuit, it will make the other bulb
off because there was no conductor for the current to flow through.
Furthermore, there were no alternative path for electron to flow
through to reach at both bulb 2 and 3.2. What happens to the other
bulbs in the circuit when bulb 2 is removed? Explain.
When bulb 2 is removed, bulb 1 and bulb 3 are still on. This is
because, the current can still flow at the other bulb or in other
words, there is another alternative path for current to reach those
bulbs.
3. Would you want the circuits in your home to be series or
parallel circuits or a combination of both? Explain your
reasoning?
For me, I prefer to the parallel circuit. This is because, it
can prevent my electrical product will not have problems because of
it. Furthermore, I can save my money too if I using the parallel
circuit in my house. This is because, the parallel circuit use
smaller voltage than the series circuit. This is true when we have
checked the voltage while doing the experiment. Conclusion: As the
conclusion, the parallel circuit is better than the series circuit.
The parallel circuit is good for us to use in our home. This is
because; it can prevent the other electrical application from
corrupt when one of them is broken. Furthermore, the voltage or
current that the parallel circuit need is lesser than the series
circuit. This meant that, it can save our money if we use the
parallel circuits at our home. Discussion:
1. From the result in activity 1, we can see that there were
differences between series circuit and parallel circuit.
2. In the parallel circuit, the reading on the ammeter and
voltmeter are same. It meant that, although the number of bulbs is
difference, the brightness of light is still same. Other than that,
the value on the ammeter and voltmeter also maintain which is 0.14
A and 1.0 V. 3. This is because in the parallel circuit, all of the
bulbs are connected at difference path. In other words, each bulb
has their own path.
4. Before that, there is a resistance in each bulb. So, the
current that flow in the circuit dose not flow through each
bulb.
5. This was the main factor why the parallel circuit has the
same reading on the ammeter and voltmeter although the number of
bulb increase or different.6. The parallel circuit is different
than the series circuit. We can see the difference in the result
for the series circuit
7. The series circuit has different reading on ammeter and
voltmeter. As we can see the value on the ammeter decrease as the
number of bulb is increase.
8. This is because; all of the bulbs were sharing the same path.
So, the current that flow through them has been decreased as it
flows through the resistance in each bulb. 9. This can make the
last bulb to be dimmest than the other because the value of the
ammeter has been decrease.
10. In the second activity, we can see that the values of
ammeter are different while the values of the voltmeter are
same.11. This is because; in the combined circuit, the voltage for
all bulbs is same but the current is different because of the
resistance in each bulb that it has flow. 12. For more information
about parallel circuit and series circuit, I have list them
below:
a) Parallel circuit1. A parallel circuit has more than one
resistor (anything that uses electricity to do work) and gets its
name from having multiple (parallel) paths to move along. Charges
can move through any of several paths.
2. If one of the items in the circuit is broken then no charge
will move through that path, but other paths will continue to have
charges flow through them. Parallel circuits are found in most
household electrical wiring.
3. This is done so that lights don't stop working just because
you turned your TV off.
4. It gets its name from having multiple (parallel) paths to
move along
5. The voltage that used in this circuit is same or equal for
every component.
6. The formulae for this circuit is: 1/RT = 1/R1 + 1/R2 + 1/R3b)
Series circuit1. 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.2. The formulae for the series circuit is
RT = R1 + R2 + R33. This circuit has a higher number of resistor4.
If we unconnected one of the bulb in the series circuit, the other
bulb will not work as usually. This is because there was no
conductor that the current or the electric can flow through.
Mastery of Knowledge and Skills Questions:
1. At the end of the practical, answer the following
questions:
a) What have you learnt from the practical?In this practical, I
have learnt about the parallel circuit and the series circuit. From
this, I know that series circuit only have one path while the
parallel circuit has another alternative path. This meant that
other component in the series circuit will not work if one of them
is broken. But, the other component in the parallel circuit will
still work as usual although there are some component did not work.
Besides that, the values for both circuit is differences in
voltage, current and resistor.b) Which part of the primary science
curriculum teaches the particular topic?
Level I (Year 1 to Year 3); Learning About the World Around Us;
Electricity. c) Discuss how you can use the above practical in your
teaching and learning? I will use the above practical in my class
so that there will be hands- on activities in my class. This is
because the students will be easily to remember and understand by
doing the activities by themselves. I also will ask them to do this
type of practical so that they will be more understood on this
topic. So, as a teacher I must use any style or tactic in my
teaching process so that the students will understand about this
topic and also can applied those concept that they have learnt in
the topic in their daily life. d) What was the role of the teacher
in the above practical?
In this practical, they were student centered which means that
the teacher just act like a facilitator to help them whenever they
have any problems. The teacher also can guide them while doing the
experiment so that there will be no problems and also can get the
accurate result or answer.
Resources:
Paul W. Zitzewitz; PhD. Physics Principles and Problems. Glencoe
McGraw- Hillhttp://en.wikipedia.org/wiki/Electronic_circuit.10.29
pm. 11 April 2010
http://en.wikipedia.org/wiki/Series_and_parallel_circuits.10.29
pm. 11 April 2010
http://cipco.apogee.net/foe/fcsps.asp.10.29 pm. 11 April
2010
http://www.allaboutcircuits.com/vol_1/chpt_5/3.html.10.29 pm. 11
April 2010
http://regentsprep.org/regents/physics/phys03/bparcir/default.htm.10.29
pm. 11 April 2010
