SW Analysis of resistance of resistors through
electrical circuits
1
Ms. K. Poongodi and 2Dr. K. Raji
1
Research Scholar
2
Associate Professor, Department of Physics,
Holy Cross College (Autonomous),
Tiruchirappalli – 620 002.
Abstract
Number of tables and graphs are drawn depending
on the observations obtained during experimental
work. Satisfactory results are obtained. Since it was
impractical to study6,7 all resistors, a simple random
sample instead was studied and predicted a range of
population values based on the sample results. The
study is limited with gold tolerance, therefore
effectively eliminating a compounding factor.
It is found that any resistor with a percentage
deviation greater than the uniform sample tolerance
level was categorized as defective. In the simple
random sample that we calculated few of the tested
resistors were defective. Only 5 were defective out of
30 in number.
common component in all kinds of electronic
equipments ranging from a small radio to colour
television receiver.
Experimental Work
A number of resistors are taken for the study. All
the resistor values are measured using digital
multimeter, using ohm’s law circuit, using internal
resistance circuit, high resistance by leakage.
A statistical analysis3 is also carried out to meet the
purpose. In Table 1 the results of few components are
illustrated. From the table it is observed that the
internal resistance observations are in relation with
original components values. The statistical analysis
shows an increase in values of resistances with
reference to original component values. Ohm’s law
circuit observations show less resistance values
compared to original resistance values. A related
graph is drawn and shown in Graph 1.
Table 1
Resistors values - Using different electrical circuits
Keywords : Accuracy, Error, Range and Standard
Deviation
Introduction
The purpose of the study is to find the proportion
of defective resistors within the arsenal of resistors
that Holy Cross College uses for laboratories. The
basic ingredients of the wide world of electronics are
small components like resistors, condensers, diodes,
transistors, IC chips etc. These are the fundamental
block1 of any electronic gadget ranging from radio to
pentium. No single component can perform any
function unless it is in connection with other required
components and has enough power supply.
Graph 1 : Resistors values - using different
electrical circuits
Rationale
Often we blame the students in their laboratory
work regarding the results obtained by them. The
curiosity arose in my mind why the students get
different results when they perform the same
experiment every day, every week and every year.
The accuracy of the result used to be very different.
In Tamilnadu during the year 2012-13, throughout the
year there was about 16 hours of power cut. Power
shut down or change of power due to the generator
may be one of the causes for the inaccuracy obtained.
Hence the investigation!
Resistors
These are the devices in various technological
instruments to control current flow2 and therefore
make the product efficient. It is probably the most
Relative accuracy and error is determined using
the mean value and is shown in Table 2.
Table 2
Percent of deviation, Error and relative accuracy
Graph 2 : Percent of deviation, Error and
relative accuracy
Graph 3 : Percent of deviation ,Error and relative
accuracy
A related graph is drawn and shown in Graph III.
The percentage deviation values are small and give
negative values. Because the calculated value in high
resistance by leakage is very much small. The relative
accuracy obtained using internal resistance method is
linear and it is in good agreement with the standard
result.
Results
A related graph is drawn and shown in Graph II.
From the above graph it is understood that the relative
accuracy is a fractional value and the error is a
minimum fraction. Mean value shows a linear scale. A
scientific experimental measurement is incomplete4,5
if one does not estimate the error of one’s result.
Table 3
Percent of deviation, Error and relative accuracy
Number of tables and graphs are drawn depending
on the observations obtained during experimental
work. Satisfactory results are obtained. Since it was
impractical to study6,7 all resistors, a simple random
sample instead was studied and predicted a range of
population values based on the sample results. The
study is limited with gold tolerance, therefore
effectively eliminating a compounding factor.
It is found that any resistor with a percentage
deviation greater than the uniform sample tolerance
level was categorized as defective. In the simple
random sample that we calculated few of the tested
resistors were defective. Only 5 were defective out of
30 in number.
Discussions
In this project various types of resistors are
brought and are connected in various circuits like
digital multimeter, ohm’s law circuit, internal
resistance circuit and high resistance by leakage
circuit. The readings have been taken and are
tabulated. The resistance values are calculated using
formula. The calculated resistance values are
compared with the original components values and the
level of achievements shown in Graph I, II & III. In
the digital multimeter circuit, the calculated resistance
values are mostly in good agreement with the
component values. But it shows small positive
correction. This may be due to the instrumental errors8
inherent in measuring because of their mechanical
structure9. The leads of the digital multimeter may
resist the circuit. Due to this there may be a chance of
random errors.
In the ohm’s law circuit, voltmeter and ammeter
are used. Due to the loading effect in the voltmeter,
small correction in this circuit is obtained. The
correction is negative for higher values. The amount
of heat developed into the circuit also one of the
causes for getting different values in the observation.
Environmental errors are due to the conditions
external to the measuring device, including the area
surrounding the instrument, such as the effects of
temperature10, humidity and barometric pressure,
magnetic or electrostatic fields.
In the internal resistance circuit, the calculated
values are exactly agreeing with the component
values. But very small correction is obtained. This
may be due to the gross errors.
In the high resistance by leakage circuit, mostly
the calculated value is not matching with the
components value and also gives negative corrections.
This may be due to the misuse of instrument and
observational errors.
Conclusion
Some of the calculated resistance values are
matched with the original components value and some
of them are not. This may be due to the occurrence of
various types of errors. The error may have occurred
due to the problem with the apparatus. So great care
should be taken while taking readings and handling
the apparatus. Instrumental errors may be avoided by,
(i)
Selecting a suitable instrument for the particular
measurement application
(ii) Applying correction factor after determining the
amount of instrumental error
(iii) Calibrating the instrument against standard
Personal or human errors are caused due to the
limitations in the human senses. For an example, one
may sometime consistently read the observed value
either high or low and thus introduce systematic errors
in the results. While at another time one may record
the observed value slightly different than the actual
reading and consequently introduce random error in
the data. Therefore it is necessary to exercise extreme
care with maturity and considered judgment regarding
the observations so as to avoid such errors. Therefore
it is understood from the above conclusion if exact
resistance value is not obtained it is not the fault of the
student.
References
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2.