Chapter II
Resistors
In life, there are many struggles and
challenges that would be encountered. In every moment, we are not expecting
that something will happen but somehow we don’t notice that these problems help
us in shaping or regulating our personality. It is important to have the key or
instrument in shaping our behaviors. And these could be associated with the
function and nature of resistors. From the word resistors themselves (resist),
they are known to be circuit elements that would function as a regulator or
controller of voltage. They resist the voltage and current those pass in the
circuit. They have two terminals in which either of them could be positive or
negative and it only depends on their orientation on a circuit. Mainly, there are
many types of resistors and these would be discussed as we move on to this page.
Before anything else, we should be acquainted on the value or measurement that
we could get in every resistors and this value is known to be the resistance.
According to Ferriols-Pavico, J., et. al., resistance is the opposition a
material offers to the flow of charges to it. The SI unit of resistance is ohm.
It is named after George Simon Ohm. It is represented By the Greek letter omega
Ω. Two symbols that we could use to represent a resistor in a circuit are the
following:
Then, I will introduce to you the factors that affect the resistance of an object. These are cross-sectional area length, kind of material and temperature.
Types of Resistor with its Composition
Different circuit elements have types. Now,
let us be oriented with the common types of resistors.
a. Carbon
Composition Resistor – This is made up of carbon dust or graphite or
graphite paste. This has low wattage values.
http://electrical4u.com/electrical/wp-content/uploads/2013/03/carbon-composition-resistor.png
b. Film or Cement
Resistor – This is made up from conductive metal oxide paste. This also
has low wattage values.
c. Wire-wound
Resistor – This is made from metallic bodies for heat sink mounting. They
have very high wattage values.
Methods in Getting the Resistance of Resistors
There are two
common methods in getting the resistance of resistors. Let us discuss them one
by one.
a. Color Coding
This method is widely used without using any
measuring device. It is just the usage of our senses and mind in getting the
resistance value. We will just observe on the bands of colors in a resistor and
check out the corresponding multipliers of colors and tolerance of the last color.
Let us consider this table of colors and their corresponding values.
http://www.radioing.com/hamradio/rcolors.gif
We should have our example.
Figure 5.
b. Using a Multitester
This method
includes the usage of a device called multitester in measuring the resistance
of a resistor. We will just put the positive and the negative prongs of the
multitester to the terminals of the resistor separately. Kindly, look at the
figure for better understanding.
We will just look on
the ohms scale in the multitester.
Circuit Connections Using Resistors
Resistors can be connected either in series,
parallel, and series-parallel connection. We will know them one by one.
a. In a series connection, the equivalent
resistance of resistors are just the summation of the individual resistance. It
could be simplified to recall using the formula:
http://www.ibiblio.org/kuphaldt/electricCircuits/DC/00082.png
b. In a parallel connection, the equivalent
resistance can be gotten using the formula:
1/Req = 1/R1 +
1/R2 + 1/R3 ...Rn.
http://www.ibiblio.org/kuphaldt/electricCircuits/DC/00083.png
c. In a series parallel connection, getting the
equivalent resistance is complicated but it would be easy when it is done in a
step by step process. Just try to look on the resistors that are connected in
parallel and get their equivalent resistance. Then, add their equivalent
resistance to the other resistors which are connected in series. It is done
through using the formulas that are stated while back.
http://www.ibiblio.org/kuphaldt/electricCircuits/DC/00084.png
To understand more on the different
connections and the relationship between resistance, voltage and current, study
the preceding data.
Experimentation:
I. Objectives:
At the end of the experiment, the experimenters are expected to:
1. apply the concept of series and parallel connection 2. differentiate series and parallel values in terms of current and voltage
1. apply the concept of series and parallel connection 2. differentiate series and parallel values in terms of current and voltage
3.point out the significance of individual differences
1. Set the resistors in series connection through the alligator clips.
2. Connect the alligator clips on both ends on the AC-DC Converter.
3. Regulate the voltage in any voltage output.
4. Read the voltage drop and current in each of the resistor.
5. Record the data in table 1.
6.Set the resistor in parallel connection and repeat procedure 2-4.
7.Record data in table 2.
IV. Data:
Series:Vout= 7.8v
Resistance
|
Resistance
Coding
|
Colors
|
Vdrop
Theoritical
|
Vdrop
Experimental
|
Current
Theoritical
|
Current
Experimental
|
R1=5500 Ω
|
5600 Ω
|
G, B, R, Gold
|
1.9085 V
|
1.8 V
|
3.47×10-4 A
|
3.25 ×10-4 A
|
R2= 350 Ω
|
350 Ω
|
O, W, Br, Gold
|
0.12145 V
|
0.12 V
|
3.47×10-4 A
|
3.25×10-4 A
|
R3=1000 Ω
|
1000 Ω
|
Br, Bl, R, Gray
|
0.347 V
|
0.31 V
|
3.47×10-4 A
|
3.25×10-4 A
|
R4=3400 Ω
|
3300Ω
|
O, O, R, Gold
|
1.1798 V
|
1 V
|
3.47×10-4 A
|
3.25×10-4 A
|
R5=4700 Ω
|
4700 Ω
|
Y, R, V, Gold
|
1.6309 V
|
1.4V
|
3.47×10-4 A
|
3.25×10-4 A
|
R6=7500 Ω
|
7500 Ω
|
V, Gr, Re, Gold
|
2.6025 V
|
2.3 V
|
3.47×10-4 A
|
3.47×10-4 A
|
Total: 22450
|
7.8 V
|
6.93 V
|
3.47×10-4 A
|
3.47×10-4 A
|
Voltage
%diff= theo-expe×100%= 7.8
V – 6.93 V ×100%= 11.15%
Theo 7.8 V
Current
%diff= theo-expe×100%=3.47x10-4A
– 3.25x10-4A×100%= 6.34%
Theo 3.47x10-4A
ParallelVout=
5.4V
Resistance
|
Resistance
Coding
|
Colors
|
Vdrop
Theoritical
|
Vdrop
Experimental
|
Current
Theoritical
|
Current
Experimental
|
R1= 5500 Ω
|
5600 Ω
|
G, B, R, Gold
|
5.4 V
|
5.4 V
|
9.8×10-4 A
|
9 ×10-4 A
|
R2= 350 Ω
|
350 Ω
|
O, W, Br, Gold
|
5.4 V
|
5.4 V
|
0.0159 A
|
0.0137 A
|
R3= 1000 Ω
|
1000 Ω
|
Br, Bl, R, Gray
|
5.4 V
|
5.4 V
|
5.4×10-3 A
|
5.5×10-3 A
|
R4= 3400 Ω
|
3300Ω
|
O, O, R, Gold
|
5.4 V
|
5.4 V
|
1.588×10-3 A
|
1.7×10-3 A
|
R5= 4700 Ω
|
4700 Ω
|
Y, R, V, Gold
|
5.4 V
|
5.4 V
|
1.149×10-3 A
|
1.2×10-3A
|
R6= 7500 Ω
|
7500 Ω
|
V, Gr, Re, Gold
|
5.4 V
|
5.4 V
|
2.2×10-3 A
|
1.2×10-3 A
|
Total: 22450
|
5.4 V
|
5.4 V
|
0.025A
|
7.3×10-4 A
|
RT=231.71Ω
Voltage
%diff= theo-expe×100%= 5.4
V – 5.4 V ×100%= 0%
Theo 5.4 V
Current
%diff= theo-expe×100%=0.025A
– 0.024×100%= 4%
Theo 0.025A
NetworkVout=
5.8V
Resistance
|
Resistance
Coding
|
Colors
|
Vdrop
Theoritical
|
Vdrop
Experimental
|
Current
Theoritical
|
R1= 5500 Ω
|
5600 Ω
|
G, B, R, Gold
|
0.25 V
|
0.0225 V
|
4.5×10-5 A
|
R2= 350 Ω
|
350 Ω
|
O, W, Br, Gold
|
0.25 V
|
0.25 V
|
7.143×10-4 A
|
R3= 1000 Ω
|
1000 Ω
|
Br, Bl, R, Gray
|
0.76 V
|
0.74 V
|
7.61×10-4 A
|
R4= 3400 Ω
|
3300Ω
|
O, O, R, Gold
|
2.59 V
|
2.4 V
|
7.61×10-4 A
|
R5= 4700 Ω
|
4700 Ω
|
Y, R, V, Gold
|
2.20 V
|
2.11 V
|
7.61×10-4 A
|
R6= 7500 Ω
|
7500 Ω
|
V, Gr, Re, Gold
|
2.20 V
|
2.11 V
|
7.61×10-4 A
|
Total: 22450
|
5.8 V
|
5.49 V
|
V. Observation:
As I have observed, one and most observable is that the current and voltage are not the same for both the current and resistor in each of the set up that we made.
VI.Questions:
2. What do you think are the factors that affect the differences in the value of current and voltage?
VII. Conclusion:
At the end of this chapter, I able to realized the importance of resistors in a circuit.
As I have observed, one and most observable is that the current and voltage are not the same for both the current and resistor in each of the set up that we made.
VI.Questions:
- What is the difference between the equivalent resistance in series and parallel connection?
2. What do you think are the factors that affect the differences in the value of current and voltage?
The factor that affect the value of current and voltage is the type of connection because it would vary the resistance.
3. What are the applications of resistors in the real life?
Resistors are commonly used in different electronic devices or appliances because of their ability to control current and voltage. Thus, these gadgets would not be damaged by the undesired current.VII. Conclusion:
At the end of this chapter, I able to realized the importance of resistors in a circuit.
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