INFORMATION AND COMMUNICATION TECHNOLOGY IN SCIENCE

( SSI 3013 )
SEMESTER 1 SESI 2016/2017
DATA LOGGING : OHMS LAW
Bil

Nama

Kumpulan

No. Matrik

1.

CHUA XIAO XUAN

D20161075225

2.

ARIFAH ADLINA BINTI RASHAHAN

D20161075231

3.

LINA ANAK KANDAU

D20161075232

4.

ANIS SYAHIRA BINTI MASROM

D20161075233

NAMA PENSYARAH: ENCIK AZMI BIN IBRAHIM

TARIKH : 2/11/2016

Introduction
A data logger is a selfcontained unit, that does not require a host to operate. It can be
installed in almost any location, and left to operate unattended. Data loggers have a distinct
advantage over conventional interface devices, in that they operate in this stand-alone
mode, and yet have the capability to transfer the data to a host system, if required. Most
data loggers have the ability to work similarly to standard recorders, in that they provide
the user with a hard copy printout of the data recorded. This data can be immediately
analyzed for trends, or stored for historical archive purposes.
Data loggers can also monitor for alarm conditions, while recording a minimum
number of samples, for economy. If the recording is of a stead-state nature, without rapid
changes, the user may go through rolls of paper, without seeing a single change in the
input. A data logger can record at very long intervals, saving paper, and can note when an
alarm condition is occurring. When this happens, the event will be recorded and any
outputs will be activated, even if the event occurs in between sample times. A record of
all significant conditions and events is generated using a minimum of recording hardcopy.
A data logger is an attractive alternative to either a recorder or data acquisition system in
many applications. When compared to a recorder, data loggers have the ability to accept
a greater number of input channels, with better resolution and accuracy. Also, data loggers
usually have some form of on-board intelligence, which provides the user with diverse
capabilities. For example, raw data can be analyzed to give flow rates, differential
temperatures, and other interpreted data that otherwise would require manual analysis by
the operator. The major difference between a data logger and a recorder, however, is the
way the data itself is stored, analyzed and recorded. A common recorder accepts an input,
and compares it to a full scale value. The pen arm is then deflected across the recording
width, to produce the appropriate ratio of the actual input to the full scale input. For
example, using a recorder with a 1 Volt full scale, an input of 0.5 Volts would move the
pen 0.5/1 or 50% of the distance across the recording width. In comparison, a data logger
accepts an input which is fed into an analog-to-digital converter prior to analysis and
storage. This method has advantages in accuracy and resolution, while only a recorder can
provide a truly continuous trend recording. Data loggers can also offer advantages over
dedicated.
The differences between various data loggers is based on the way that data is
recorded and stored. The basic difference between the two data logger types is that one
type allows the data to be stored in a memory, to be retrieved at a later time, while the

other type automatically records the data on paper, for immediate viewing and analysis.
Many data loggers combine these two functions, usually unequally, with the emphasis on
either the ability to transfer the data or to provide a printout of it.
For users who must acquire data over many locations, and wish to have a single
collection/recording point, networking is a truly viable solution. With a network, one
central location is responsible for data storage and recording; data is collected by remote
units in various locations, and then fed to this master unit for storage/recording. This is
a great convenience, in that an operator can retrieve the data from one location, rather than
having to go to each individual site for collection.
The advantages of the local hard copy data loggers are that:
1. The operator has a permanent recording on paper,
2. No other external or peripheral equipment is required for operation
3. Have the ability to record data trends, in addition to simple digital data recording.
In comparison, units with internal data storage tend to be more compact, due to the fact
that no paper and recording equipment are required, and because they are much simpler
electronically and mechanically. Data storage units are usually more economical. These
units can also be operated in a stand-alone mode, with the ability to feed or download data
to a host computer system.
In our daily life, there are a lots of application of data logging. For the example,
unattended weather station recording which measure the wind speed and direction,
temperature, relative humidity and solar radiation. Data logging also can be use in water
level monitoring for groundwater studies and measure variations light intensity. Data
logger also can be divided as black-box loggers, health data loggers and other general data
acquisition loggers. A flight data recorder (FDR) is a black-box logger, which is a piece
of recording equipment used to collect specific aircraft performance data. The term may
also be used, albeit less accurately, to describe the cockpit voice recorder (CVR), another
type of data recording device found on board aricraft. The health data loggers is used is
the growing, preparation, storage and transportation of food. Data logger is generally used
for data storage and these are small in size. The other general data acquisition loggers is
an scientific experimental testing data acquisition tool.
Data Loggers are changing more rapidly now than ever before. The original model
of a stand-alone data logger is changing to one of a device that collects data but also has
access to wireless communications for alarming of events, automatic reporting of data

and remote control. Data loggers are beginning to serve web pages for current readings, email their alarms and file transfer protocol (FTP) their daily results into databases or
direct to the users. Very recently, there is a trend to move away from proprietary products
with commercial software to open source software and hardware devices. There are more
and more community-developed projects for data acquisition / data logging.

Engage
Resistance is the electrical property that opposes the current flow in an electric circuit.
The unit of resistance is Ohm (). A resistor is an electronic component design purposely
to limit the current flow by dissipating heat. The physical size of resistor is related to its
wattage. Small resistor has lower wattage and vice versa. One property that all resistors
share is that they act as conductors under certain conditions. The inverse of this is also
true, hence the terms conductor and resistor are partially interchangeable, and the
resistance through a conductor can be measured in the same way as a resistor.
There are two types of conductors, Ohmic and Non-Ohmic. Ohmic conductors
are conductors that adhere strictly to Ohms law of I=V/R, where I is the current, V the
potential difference and R the resistance, at least over a certain temperature range, and
hence have a direct relationship between the current flowing through the conductor or
resistor and the corresponding resistance. Non-ohmic conductors are conductors which
do not obey Ohms law over varying temperatures, and thus have varying resistances.
The electrical resistance R of a conductor is defined as the ratio of the potential
difference, or voltage, V, applied across the conductor to the current I that passes through
it:
R=

If the conductor is made of a homogeneous material formed into a shape of

uniform cross-sectional area A and length l, the resistance can be expressed in terms of
these dimensions and an intrinsic property of the material called its resistivity:
=

In this expression, represents the resistivity of the material.

The resistivity of many materials, including most metals, depends on the material's
temperature but does not depend on the applied voltage (or, more properly, on the electric
field in the material). If the resistance of a device does not depend on the applied voltage,

the device is said to obey Ohm's Law, or to be "ohmic." Devices for which the resistance
depends on the applied voltage are called "non-ohmic."
The carbon resistor you will study is an ohmic device, while the diode is a nonohmic device. The filament in the light bulb is made of an ohmic material, but the light
bulb's resistance will change as you change the applied voltage. Thus, the light bulb is
a non-ohmic device. The resistance of the bulb changes because the filament heats up,
and the resistivity of the filament material depends on its temperature. If you could keep
the temperature of the filament constant as you changed the voltage, its resistance would
also remain constant. Ohms Law states that the voltage across the ends of a conductor
is directly proportional to the current flowing through it, provided that the temperature
and the other physical condition are unchanged.

Empower
The objective of this experiment is to investigate the relationship of voltage and current
of a light bulb and a resistor. In this experiment, we study Ohms law by examining the IV characteristics of a fixed resistor and a tungsten filament (bulb). A resistor is said to be
ohmic if the value of the resistance of that object is constant independently from the
applied voltage and current respectively. Whether an object is an ohmic or non-ohmic
resistor can also be investigated by drawing a resistance-current graph and by calculating
the resistances for each applied voltage respectively.

Apparatus:
Light bulb, Resistor, Ammeter, USB Digital multimeter, Rheostat, Connecting wires,
Resistor, Voltage-current sensor.

USB
Digital
multimeter

Procedure:
1.

Set up the apparatus as shown in Figure 1 below.

Figure 1
2.

Connect the resistor in series with a rheostat, batteries 6V and an ammeter.

3.

Connect a USB digital multimeter across the resistor.

4.

Move the sliding contact of the rheostat to the end to maximize its resistance.

5.

By changing the resistance of your rheostat, take the ammeter and voltmeter
reading. Take as many sets of data as possible. Record your data as suggested in
table.

6.

Replace the resistor with a light bulb, and repeat step 1-5.

7.

Plot a graph of the voltage-current for both devices, a light bulb and resistor.

Results:
A. Resistor
Voltage across the resistor, V/(V)

Current through the resistor, I/(A)

B. Light Bulb
Voltage across light bulb, V/(V)

Graph:

Current through the light bulb, I/(A)

Questions:
1. Draw schematic diagram of the circuit in Figure 1.

2. From the graph, describe the way to calculate resistance of both devices.

Formula R= is used to calculate resistance across resistor and light bulb. In graph,
V=IR, v is in y-axis while I is in x-axis. R is the gradient of graph.

3. Describe the shape of both graphs.

Graph voltage across resistor, V/(V) against current through resistor, I/(A) shows
the nature of the relationship between voltage with current in linear and directly
proportional distribution, which voltage is increasing linearly with the increasing of
current. Graph voltage across the bulb, V/(V) against current through the bulb, I/(A)
shows the nature of the relationship between voltage with current in in exponential
distribution.

4. What is the conclusion of your finding?

From graph voltage across resistor, V/(V) against current through resistor, I/(A), the
results are accurate as almost every point of data is attached with line of graph. From
graph voltage across the bulb, V/(V) against current through the bulb, I/(A) using
light bulb our results, we found that resistance at every point of line graph is different.
Determining the resistance of a bulb with multimeter is inaccurate. The filament has
a positive temperature coefficient. This means its resistance rises with temperature.
When cold we will get a few ohms of resistance, but at operating temperature, expect
it to rise dramatically. So, the reading of resistance of bulb that was taken from
multimeter is its resistance when its cold. As we connected light bulb to circuit, its

temperature will increase gradually. When temperature of bulb increases, its

resistance will increase. Surely, upon an increase in temperature, the atoms within
the filament of bulb would vibrate with more energy and therefore more vigorously,
hence making the electrons flowing through the electric circuit more likely to collide
with one of the atoms, so increasing resistance. In conclusion, resistor is an ohmic
conductor while obey Ohms Law while bulb is non-ohmic conductor which does
not obey Ohms Law.
Enhance
Ohms law is the most fundamental law of electrical branch. The application of Ohms
law ranges from household electrical circuit and equipment designing to high tension
wires, transformers and generators designing. The main application of Ohm's Law is
used when building electrical devices. Most appliances need a certain amount of voltage
and current to operate. To figure out the most efficient way to get the proper current,
Ohm's Law is used. It relates voltage and current in any conductor. The ratio of applied
voltage and current flowing through that conductor gives you resistance to the current
in the conductor and measured in ohms. This resistance creates heating when current
flows in it. Using Ohms law, we can determine the resistance and design our circuit
and equipment as per the requirement.
Resistors are very important in electric circuits. They are used to limit the
amount of current traveling through the circuit and to establish certain levels of voltage.
Ohm's Law is used to figure out which resistors are needed. Without Ohm's Law, we
wouldn't be able to figure out how much resistance is needed in a circuit, and therefore
either too much or too little current or voltage would be produced.
There are many examples of practical applications in whose working principle
is based on this law. The followings are some of devices that apply Ohms Law to
function properly.

Alternator/Synchronous Generator
Modern day generation of electrical power uses Alternator/Synchronous
generator. The internally generated voltages are based on flux which in turn uses
Resistance/current relationships of rotors winding. This flux directly depends
on internal current. For decreasing/increasing this current the field resistance
can be varied. This entire Resistance/Current relationship is also a part of Ohm's
statement.

DC Power Supply
DC Power Supply is commonly used in laboratories for providing a voltage
ranging from 0-30V (most commonly). The variable voltage between these
ranges uses the application of potentiometer. In potentiometer, the resistance is
increased/decreased to increase/decrease the amount of output voltage. This
increment/decrement of voltage and resistance are based on the Ohm's Formula
V = IR.

Electric Iron, Heaters and Kettles

Electric Iron, heaters and kettles are also the applications of Ohm's and they use
the same working principle as explained in previous examples. Heat is being
produced by a current carrying conductor, the resistance of that conductor is
responsible for this heat production.

Mobile Phone & Laptop Charger

Mobile phone & laptop chargers use DC power supply in operations. As
described earlier that working of this supply depends on the Ohms law.

Resistive filament bulb

Although not widely employed today, the old days filament bulb holds the
application of P =VI (a modified form of V = IR)

The other equipment which uses similar applications of law in their working:
Rocket, Space Ship, Solid state Electronics, BJT Transistor, Amplifiers, Electronic
Circuits.

Conclusion
Data logging is the process of using a computer to collect data through sensors, analyze
the data and save and output the results of the collection and analysis. It implies the
control of how the computer collects and analyzes the data. It is commonly used in
scientific experiments and in monitoring systems where there is the need to collect
information faster than a human can possibly collect the information and in cases where
accuracy is essential. Examples of the types of information a data logging system can
collect include temperatures, sound frequencies, vibrations, times, light intensities,
electrical currents, pressure and changes in states of matter.
In this experiment, we used USB digital multimeter which acts as data logger
when is connected to computer. With this device, we can measure voltage, current and
resistance in the circuit. Software such as Data Studio is required to obtain and record
every data read from multimeter. Its convenient to use data logger in experiment as the
software can record data in table and also plot graph using collected data.
From this experiment, we know that the main difference between an ohmic and
a non-ohmic conductor is whether they follow Ohms law. An ohmic conductor would
have a linear relationship between the current and the voltage. With non-ohmic
conductors, the relationship is not linear. Resistor is an ohmic conductor. The voltage
drop across a resistor is directly correlated to the current that is flowing through it.
Non-ohmic conductors do not follow Ohms law and have their own
characteristics. There are a number of examples of non-ohmic conductors; including
bulb filaments and semiconductors like diodes and transistors. For instance, a diode
provides a near constant voltage drop even if you vary the current, so it does not follow
Ohms law. The opposite happens in a light bulb filament; even as you increase the
voltage significantly, it only allows a certain amount of current to pass through.

References:
1. http://www.onsetcomp.com/files/data-logger-basics.pdf.
2. Giambattista, A., Richardson, B.M., and Richardson, R.C. (2008).

College

Physics. Boston, MA: McGraw-Hill.

3. Giancoli, D.C. (2005). Physics: Principle with Application (6th Ed.). Upper
Saddle River, NJ: Prentice Hall.