1.
What
is resistor?
A resistor is an electrical/Electronics component that limits or regulates the flow of
electrical current in an electronic circuit.
2
Type of resistor?
There are two basic types of resistors.
1. Linear Resistors
2. Non Linear Resistors
1. Linear Resistors:
Those
resistors, which values change with the applied voltage and temperature, are
called linear resistors. In other words, a resistor, which current value is
directly proportional to the applied voltage is known as linear resistors.
Generally,
there are two types of resistors which have linear properties.
1.1.FixedResistors
1. 2. Variable Resistors
1. 2. Variable Resistors
1. 1. Fixed Resistors
As
the name tells everything, fixed resistor is a resistor which has a specific
value and we can’t change the value of fixed resistors.
Types of
Fixed resistors.
1.
Carbon Composition Resistors
2.
Wire Wound Resistors
3.
Thin Film Resistors
4.
Thick Film Resistors
1.
2) Variable Resistors
As the
name indicates, those resistors which values can be changed through a dial,
knob, and screw or manually by a proper method. In these types of resistors,
there is a sliding arm, which is connected to the shaft and the value of
resistance can be changed by rotating the arm. They are used in the radio
receiver for volume control and tone control resistance.
Following
are the further types of Variable Resistors
1.Potentiometers
2.Rheostats
3. Trimmers
2.Rheostats
3. Trimmers
2.
Non Linear Resistors
We know
that, nonlinear resistors are those resistors, where the current flowing
through it does not change according to Ohm’s Law but, changes with change in
temperature or applied voltage.
In
addition, if the flowing current through a resistor changes with change in body
temperature, then these kinds of resistors are called Thermisters. If the
flowing current through a resistor change with the applied voltages, then it is
called a Varistors or VDR (Voltage Dependent Resistors).
Following
are the additional types of Non Linear Resistors.
1.Thermisters
2.Varisters(VDR)
3. Photo Resistor or Photo Conductive Cell or LDR
2.Varisters(VDR)
3. Photo Resistor or Photo Conductive Cell or LDR
3.
Calculate
the value of resistor?
Identifying Resistor Values
Band Colour
|
1st
Band
|
2nd Band
|
Multiplier
x
|
Tolerance
|
Silver
|
100
|
10%
|
||
Gold
|
10
|
5%
|
||
Black
|
0
|
0
|
1
|
|
Brown
|
1
|
1
|
10
|
1%
|
Red
|
2
|
2
|
100
|
2%
|
Orange
|
3
|
3
|
1000
|
|
Yellow
|
4
|
4
|
10,000
|
|
Green
|
5
|
5
|
100,000
|
|
Blue
|
6
|
6
|
1,000,000
|
|
Violet
|
7
|
7
|
||
Grey
|
8
|
8
|
||
White
|
9
|
9
|
Example: Band 1 = Red, Band 2 = Violet, Band 3
= Orange, Band 4 = Gold
The value of this resistor would be:
2
(Red) 7 (Violet) x 1,000 (Orange) =
27 x 1,000
= 27,000 with a 5% tolerance (gold)
= 27kΩ
Resistor Identification Task
Calculate the resistor values given by the
bands shown below. The tolerance band has been ignored.
1st Band
|
2nd Band
|
Multiplier
x
|
Value
|
Brown
|
Black
|
Yellow
|
|
Green
|
Blue
|
Brown
|
|
Brown
|
Grey
|
Yellow
|
|
Orange
|
White
|
Black
|
What does tolerance mean?
Resistors always have a tolerance but what
does this mean? It refers to the accuracy to which it has been manufactured.
For example if you were to measure the resistance of a gold tolerance resistor
you can guarantee that the value measured will be within 5% of its stated
value. Tolerances are important if the accuracy of a resistors value is
critical to a designs performance.
4.
Resistor
test and identify?
1.
Remove power from the
circuit containing the resistor. ...
2.
Isolate the resistor
from the circuit. ...
3.
Inspect the resistor.
...
4.
Read the resistor
value visually. ...
5.
Prepare a digital
multimeter (DMM) to measure the resistor. ...
6.
Measure the
resistance. ...
7.
Determine the actual
resistance of the resistor.
5 . Application
of resistor?
Uses
/ Application of Resistors
Practically,
both types of resistors (Fixed and Variable) are generally used for the
following purposes.
Resistors are used:
Resistors are used:
1.For Current
control and limiting
2.To change
electrical energy in the form of heat energy
3. As a
shunt in Ampere meters
4. As a
multiplier in a Voltmeter
5. To control
temperature
6. To control
voltage or Drop
7. For
protection purposes, e.g. Fusible Resistors
8. . Widely used
in the electronics industries
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